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October 2023
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  1. Brookhaven Women in Science (BWIS) Activity

    "How Inclusion Impacts an Organization's Sustainability"

    Toni L Carter, INL

    Wednesday, July 27, 2022, 4 pm
    Videoconference / Virtual Event

    Hosted by: Vivian Stojanoff

    Registration is free and required

  2. Nuclear Physics & RIKEN Theory Seminar

    "Entanglement minimization in hadronic scattering"

    Presented by Silas R Beane, University of Washington

    Friday, June 11, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Yacine Mehtar-Tani

    Abstract: Recent work has found that entanglement minimization in low-energy baryon-baryon scattering leads to enhanced symmetry, which is distinct from large-N QCD expectations, and which is confirmed in lattice QCD simulations. I will review these developments and then I will present very recent work which considers implications of entanglement minimization for pion-pion and pion-baryon scattering.

  3. Nuclear Physics & RIKEN Theory Seminar

    "Toward understanding the high-baryon state of matter"

    Presented by Kenji Fukushima, The University of Tokyo

    Friday, June 4, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Semeon Valgushev

    Abstract: I will talk about three approaches to deepen our understanding of the high-baryon state of matter: The first one is the pQCD analysis with the effect of resummation. It is said that the pQCD EoS is uncertain unless the baryon density is unphysically large, but this is caused by an improper choice of small scale. A simple resummation can change the situation drastically to narrow the uncertainty band. The second one is the interacting hadronic model that complements the pQCD analysis, but an excluded volume effect with hard core would easily violate the causality. I will discuss that the Carnahan-Starling implementation of the smeared interacting core works well with phenomenology. Finally, I will introduce a bit of academic thinking about nuclear matter under strong magnetic fields described by the Skyrme model, which is however rather model independent in a sense that the important physics is brought in by the anomalous coupling between the density and the magnetic field.

  4. High-Energy Physics & RIKEN Theory Seminar

    "Discovering Lepton Flavour Universality Violating New Physics"

    Presented by Andreas Crivellin, CERN

    Thursday, June 3, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: While the LHC has not discovered any new particles directly yet, hints for the violation of lepton flavour universality (satisfied within the SM) accumulated in recent years. In particular, deviations from the SM predictions were observed in semi-leptonic B decays (b->sll and b->ctau), in the anomalous magnetic moment of the muon (g-2), in leptonic tau decays and di-electron searches. Furthermore, also the deficit in first row CKM unitarity, known as the Cabibbo Angle Anomaly, can be interpreted as a sign of lepton flavour universality violation. In this talk I review the status of these anomalies and give an overview of the possible interpretations in terms of new physics models.

  5. Nuclear Physics & RIKEN Theory Seminar

    "Single Transverse-Spin Asymmetry and Sivers Function on Lattice"

    Presented by Dr Feng Yuan, Lawrence Berkeley National Lab

    Friday, May 28, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    Abstract: This is not a lattice talk. Instead, I will present our recent development on how to formulate the quark Sivers function on Lattice based on the so-called large momentum effective theory. In particular, we argue the spin asymmetry defined as the ratio of the quark Sivers function over the spin averaged distribution can be directly calculated in terms of the relevant quasi distributions with the soft functions and perturbative matching kernels cancelling out. We will give explicit results at one-loop order, which reduces to a collinear expansion at twist-three level. This may lead to an alternative way to simulate the quark-gluon-quark correlation function (twist-3 distribution) on lattice. Reference: 2011.13397 [hep-ph]

  6. Nuclear Physics & RIKEN Theory Seminar

    "Thermal gravitational wave production in the Early Universe"

    Presented by Jacopo Ghiglieri

    Friday, May 21, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Yacine Mehtar-Tani

    Abstract: Any plasma in thermal equilibrium emits gravitational waves. In this talk, I show that, for wavelengths longer than the microscopic mean free path, the production is sourced by hydrodynamic fluctuations, while for wavelengths of the order of the inverse temperature it is sourced by scatterings. This latter mechanism is the leading one and I will show a consistent computation for a Standard Model plasma to leading order in coupling constants. I will show how the energy density of these thermally produced gravitational waves accumulates over the thermal history of the universe, contributes to the Neff parameter and constrains the highest temperature of the universe. The current theoretical uncertainty ?Neff ≤ 0.001 corresponds to Tmax ≤ 2e17 GeV. I will show throughout the presentation how the methods and physical picture are related to analogous calculations for the QCD plasma.

  7. High-Energy Physics & RIKEN Theory Seminar

    "Non-unitary neutrino oscillations to reduce tension between the NOvA and T2K data"

    Presented by Soebur Razzaque, University of Johannesburg

    Thursday, May 20, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: The unitary PMNS matrix is the parametrization used for mixing of three active neutrinos. In case there are extra neutrinos which are heavy iso-singlets, the effective mixing matrix for the three active neutrinos will be non-unitary. As a result, the oscillation probabilities between the active neutrinos are modified from the probabilities obtained using the PMNS matrix. Long baseline neutrino experiments can probe the non-unitarity and constrain parameters of the model. We have analyzed the latest data from the NOvA and T2K experiments using both the unitary and non-unitary mixing scenarios. In this talk I will present results from our analysis and show that the tension between the oscillation data from these two experiments can be reduced when analyzing with non-unitary mixing of the neutrinos.

  8. Nuclear Physics & RIKEN Theory Seminar

    "An attempt for deriving nuclear physics by holography"

    Presented by Prof. Koji Hashimoto, Kyoto University

    Friday, May 14, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    Abstract: Holographic description of QCD is capable of reproducing various hadronic observables. In this talk I will apply the holographic principle to multi-baryon systems, and attempt to derive important disciplines of nuclear physics: nuclear density saturation, nuclear binding energy and nuclear magic numbers.

  9. High-Energy Physics & RIKEN Theory Seminar

    "Adventures in the ALPs — Effective Lagrangians, flavor observables and indirect searches for axion-like particles"

    Presented by Matthias Neubert, U. of Mainz

    Thursday, May 13, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: Axions and axion-like particles (ALPs) appear in many well-motivated extensions of the Standard Model (SM). Their couplings to SM particles can be described in a model-independent way using effective Lagrangians. I will discuss the RG evolution of these couplings from the new-physics scale down to low energies, as well as the first consistent matching of a generic ALP model onto the weak chiral Lagrangian. Phenomenological implications for flavor physics and for the anomalous magnetic moment of the muon will also be presented. Finally, I will describe how even a light ALP necessarily affects the RG evolution of the dimension-6 operators in the SMEFT starting at a high scale, and how this ALP-SMEFT interference can be used to systematically search for indirect ALP effects on precision observables.

  10. High-Energy Physics & RIKEN Theory Seminar

    "Muon magnetic moment: new physics or not?"

    Presented by Kalman Szabo, University of Wuppertal

    Thursday, May 6, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: We compute the leading order hadronic vacuum polarization contribution to the muon magnetic moment from lattice QCD. The result is somewhat larger, than the traditional experimental data-driven determination (R-ratio method). The recent Fermi National Laboratory measurement of the muon magnetic moment, which has been claiming strong hint of new physics beyond the Standard Model, is now put into a different perspective. Our result is compatible with the no new physics scenario.

  11. High-Energy Physics & RIKEN Theory Seminar

    "Precision Predictions for Higgs Boson Production"

    Presented by Alexander Huss, CERN

    Thursday, April 29, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: The precise determination of the properties of the Higgs boson—the first and only elementary scalar particle we have observed—is among the highest priorities of the LHC programme and possible future colliders. I will present state-of-the-art precision calculations for Higgs production in the gluon-fusion process and discuss their impact on the interpretation of hadron-collider data.

  12. Nuclear Physics & RIKEN Theory Seminar

    "Efficient integration of gradient flow in lattice gauge theory and properties of low-storage commutator-free Lie group methods"

    Presented by Alexei Bazavov, Michigan State University

    Friday, April 23, 2021, 9:15 am
    Videoconference / Virtual Event

    Hosted by: Semeon Valgushev

    Abstract: Gradient flow is a smoothing procedure that suppresses ultraviolet fluctuations of gauge fields. It is often used for high-precision scale setting and renormalization of operators in lattice QCD calculations. The gradient flow equation is defined on the SU(3) manifold and therefore requires geometric, or structure-preserving, integration methods to obtain its numerical solutions. I discuss the properties of the three-stage third-order Runge-Kutta integrator introduced by Luescher (that became almost the default choice in lattice QCD applications) and its relation to structure-preserving integrators available in the literature. I demonstrate how classical low-storage Runge-Kutta methods can be turned into structure-preserving integration methods and how schemes of order higher than three can be built. Based on the properties of the low-storage schemes I discuss how the methods can be tuned for optimal performance in lattice QCD or any other applications.

  13. High-Energy Physics & RIKEN Theory Seminar

    "Relaxing the Cosmological Constant and Dark Energy Radiation"

    Presented by David Kaplan, Johns Hopkins University

    Thursday, April 22, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: The smallness of the cosmological constant has yet to be understood in our current theories of nature. I will argue that a dynamical (and non-antropic) explanation suggests that today's dark energy has a dynamical component. I will show that if dark energy evolves in time, its dynamical component could be dominated by a bath of dark radiation. Within current constraints this radiation could have up to ∼103 times more energy density than the cosmic microwave background. I will show models that produce different forms of dark radiation such as hidden photons, milli-charged particles and even Standard Model neutrinos. I will also show that the late-time cosmology is potentially distinguishable from a cosmological constant or normal quintessence. If the radiation couples to the standard model, it may be directly testable in laboratory experiments!

  14. High-Energy Physics & RIKEN Theory Seminar

    "Dark matter goes nuclear: the role of bound states in thermal decoupling"

    Presented by Kalliopi Petraki, Sorbonne Universite and LPTHE Paris

    Thursday, April 15, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: The production of dark matter via thermal decoupling from the primordial plasma, and the direct, indirect and collider signals associated with this mechanism, have been the pillars of dark matter phenomenology in the past decades. In sharp contrast to the sub-TeV regime, the interactions of thermal-relic dark matter with multi-TeV or larger mass manifest as long-range. This is supported by unitarity arguments, and shown by explicit calculations in WIMP and other models. The long-range nature of the interactions gives rise to non-perturbative effects, with the most prominent being the existence of bound states. The formation and decay of unstable bound states in the early universe decrease the dark matter density, thereby changing its predicted mass and/or couplings. This can have severe implications for all experimental probes, particularly for collider and indirect searches.

  15. Nuclear Physics & RIKEN Theory Seminar

    "High-energy OPE for polarized DIS"

    Presented by Dr. Chirilli Giovanni, Regensburg

    Friday, April 9, 2021, 9:15 am
    Videoconference / Virtual Event

    Hosted by: Yacine Mehtar-Tani

    Abstract: High-energy Operator Product Expansion is a formalism to study scattering amplitudes at high-energy (Regge limit) in perturbation theory. When it is applied to the product of two electromagnetic currents, we may write the unpolarized DIS amplitude as a convolution of coefficient functions and matrix elements of Wilson lines. The energy dependence of the cross-section is encoded in the Balitsky-Kovchegov evolution equation. To study polarized scattering processes one has to include sub-eikonal corrections into the OPE formalism. I will discuss the OPE of two electromagnetic currents with sub-eikonal terms: I will present new impact factors, matrix elements of new operators which are parametrized by new quark and gluon distributions, and present new high-energy evolution equations.

  16. High-Energy Physics & RIKEN Theory Seminar

    "Single Leptoquark Solutions to the B-physics anomalies"

    Presented by Florentin Jaffredo, IJCLab Orsay

    Thursday, April 8, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: Recent results from LHCb and B-factories hint at violation of Lepton Flavor Universality (LFU) in both tree-level and loop-induced B-meson decays. After a brief review of the status of these anomalies, we will discuss the minimalistic scenarios of New Physics at the O(TeV) scale which involve one leptoquark state (LQ) and which are consistent with a number of measured low energy flavor physics observables, as well as with the direct searches at the LHC. We will show which LQ can provide acceptable solution to these anomalies, and make predictions regarding the lepton flavor violating decay modes that can be probed experimentally and therefore test the validity of the proposed scenarios.

  17. Nuclear Physics & RIKEN Theory Seminar

    "Revisiting the concept of relativistic charge distribution"

    Presented by Cédric Lorcé, CPHT - Ecole Polytechnique

    Friday, April 2, 2021, 9:15 am
    Videoconference / Virtual Event

    Hosted by: Yacine Mehtar-Tani

    Abstract: We review and revisit the concept of charge distribution in the relativistic context. Adopting a phase-space perspective allows us to discuss the momentum dependence of these distributions and to connect the well-known pictures in both the Breit frame and the infinite-momentum frame. In particular, we explain why the center of the neutron charge distribution appears to be negative in the infinite-momentum frame and positive in the Breit frame.

  18. High-Energy Physics & RIKEN Theory Seminar

    "Discovering the new physics of g-2 with a muon collider"

    Presented by Yonatan Kahn, University of Illinois

    Thursday, April 1, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: As we all eagerly await the results of the Fermilab g-2 experiment, I will entertain the possibility that the long-standing discrepancy between the theoretical and experimental values of the muon anomalous magnetic moment arises from new physics. I will argue that the value of the discrepancy imposes a firm boundary on the parameter space of any new physics explanation, such that observables which confirm the anomaly are guaranteed through a combination of muon fixed-target and collider experiments up to 30 TeV center of mass energy. I will further explain that if new particles are not seen directly (either through missing energy or new charged tracks) at a 30 TeV muon collider, this would indicate an explicit fine-tuning problem in the Higgs potential arising from finite, well-defined quantum corrections and would provide persuasive evidence that nature is fine-tuned.

  19. Nuclear Physics & RIKEN Theory Seminar

    "Understanding Heavy Quark-AntiQuark System by Perturbative QCD"

    Presented by Prof. Yukinari Sumino, Tohoku University

    Friday, March 19, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    Abstract: Due to the discovery of renormalon cancelation, understanding of the heavy quark mass and interquark force was improved drastically around 1998. I overview what was understood then and theoretical progress that took place after it. We show how to extract genuine UV part of the leading Wilson coefficient in OPE of the static QCD potential and how it improves the theory prediction in the range r*Lambda_QCD

  20. High-Energy Physics & RIKEN Theory Seminar

    "Mixed QCD-electroweak corrections to vector boson production and their impact on the W-mass measurement by Raoul Rontsch (CERN)"

    Presented by Raoul Rontsch

    Thursday, March 18, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract:Measuring the mass of the W boson is an important check on the consistency of the Standard Model. The target precision for measurements of the W boson mass at the Large Hadron Collider is O(10 MeV), i.e. about 0.1 per mille. Achieving this degree of precision will require extremely good theoretical control on all aspects of vector boson production, including the simultaneous effects of QCD and electroweak corrections. I will describe a recent calculation of these mixed QCD-EW corrections to W and Z boson production, and discuss their impact on the measurement of the W boson mass.

  21. High-Energy Physics & RIKEN Theory Seminar

    "Neutrinos from Primordial Black Holes, an opera in two acts"

    Presented by Yuber Perez-Gonzalez, Fermilab & Northwestern

    Thursday, March 11, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: Hawking radiation offers a unique method of neutrino production, unlike any weak interaction process. Moreover, black hole evaporation depends on whether neutrinos are Dirac or Majorana, providing a different phenomenology in each case. If neutrinos are Dirac particles, the emission of the light right-handed states does not suffer from the helicity suppression present in weak interactions. Hence, it is possible to have a significant fraction of such states as relics from the Early Universe. On the other hand, if neutrinos are Majorana, heavy right-handed states like those appearing in the seesaw mechanism can be produced by a black hole, altering thermal leptogenesis and thus the baryon asymmetry. In this talk, we will explore these two different possibilities.

  22. Nuclear Physics & RIKEN Theory Seminar

    "Quantum anomalous energy and proton mass decomposition"

    Presented by Dr Yizhuang Liu, Regensburg

    Friday, March 5, 2021, 9:15 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    Abstract: I will discuss issues related to the proton mass decomposition and in particular, the role played by the anomalous term. I will first show that the form of the mass decomposition crucially depends on the regularization scheme, or more precisely , depends on whether there is a cutoff in temporal direction. I will show that in symmetric cutoff theory, the existence of an anomalous term is manifest and can be traced back to the construction of isotropic cutoff theory. Then I will use 1+1 non-linear sigma model in large N limit as an example to demonstrate the above points by studying the mass structure in various cutoff schemes. I will argue that the mass generation through trace anomaly can be viewed as dynamical higgs effect. Finally, I will comment on the possibility of probing the gluon content of nucleon through photo production of Ji/Psi.

  23. High-Energy Physics & RIKEN Theory Seminar

    "Mixed EW-QCD two-loop amplitudes for Drell-Yan dilepton production"

    Presented by Andreas von Manteuffel, MSU

    Thursday, March 4, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: Drell-Yan production of a charged lepton pair is a key process at the Large Hadron Collider. The region of large invariant mass region is of particular interest for new physics searches, which motivates precise theory predictions at energies well above the Z resonance. In this talk, I discuss our recent calculation of the mixed electroweak-QCD two-loop amplitudes for the process qq->l+l- as a further step in this direction. I present the calculation in two different approaches, the 't Hooft-Veltman-Breitenlohner-Maison (HVBM) gamma5 scheme and Kreimer's anticommuting gamma5 scheme, and discuss how one arrives at scheme-independent results. Solving the master integrals in terms of multiple polylogarithms of algebraic arguments, we obtain fully analytic results for the helicity amplitudes, which allow for fast and robust numerical evaluations in Monte-Carlo programs.

  24. RIKEN seminar

    "Pinning down pQCD modifications of in-medium jet evolution with substructure observables"

    Presented by Paul Caucal, BNL

    Thursday, March 4, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Akio Tomiya

    Abstract: Jet substructure techniques are powerful tools to probe the perturbative regime of jet evolution in proton-proton and heavy-ion collisions. Over the past few years, a wide variety of substructure observables have been proposed in order to pin down specific aspects of jet dynamics in a quark-gluon plasma. In this talk, I will review some of them, such as Soft Drop, Lund plane and Dynamical Grooming observables. Within a factorized picture for jet radiations in a dense medium, I will try to highlight the main perturbative mechanisms which drive the medium modifications of these observables.

  25. Nuclear Physics & RIKEN Theory Seminar

    "The D-term and forces inside hadrons"

    Presented by Prof. Peter Schweitzer, Connecticut U.

    Friday, February 26, 2021, 9:15 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    Abstract: The D-term is, like mass and spin, one of the particle properties directly related to the matrix element of the energy-momentum tensor. But, unlike mass and spin, nearly nothing is known about this property experimentally. This fact as well as the physically appealing interpretation of the D-term form factor in terms of the mechanical forces inside hadrons has triggered a lot of interest in literature. Recent theoretical, phenomenological and experimental advances are presented.

  26. High-Energy Physics & RIKEN Theory Seminar

    "Variations on the Maiani-Testa approach and the inverse problem"

    Presented by Mattia Bruno, CERN

    Thursday, February 25, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Peter Boyle

    Abstract: The Monte Carlo methods used in Lattice QCD simulations rely on the rotation of the path integral to Euclidean metric. Unfortunately, the limited knowledge of correlation functions on finite subsets of points prevents a direct analytic continuation to Minkowski signature. In their seminal publication of 1990, Maiani and Testa showed that physical amplitudes away from threshold cannot be directly extracted, ie without an inverse problem, from Euclidean correlators, due to off-shell contaminations. In this presentation, I revisit and extend their original work, and explore the connection with recent developments on the inverse problem in Lattice QCD.

  27. Nuclear Physics & RIKEN Theory Seminar

    "Energy loss of QCD jets in heavy-ion collisions"

    Presented by Konrad Tywoniuk, University of Bergen

    Friday, February 19, 2021, 9:15 am
    Videoconference / Virtual Event

    Hosted by: Yacine Mehtar-Tani

    Abstract: The quark-gluon plasma (QGP) created in high-energy heavy-ion collisions at RHIC and LHC is opaque to energetic and heavy particles that are created in short-distance particle scattering. Jets, aligned collections of energetic hadrons resulting from the fragmentation of fundamental quarks and gluons that are collected within a cone of radius R, are of special interest since they develop on time-scales comparable to the lifetime of the plasma. Jet ``quenching'', or the suppression of the jet yield at large transverse momentum, is therefore a probe not only of the elastic and inelastic interactions with the medium, but also of the medium's capability to resolve correlated QCD color charges. The energy removed from the jet is redistributed in modes that span hard collinear gluon radiation (bremsstrahlung) to softer excitations that ultimately thermalize with the surrounding medium. The radius dependence of the jet spectrum is particularly sensitive to the rich physics outlined above. In the first part of the talk, I will present a recent calculation of the jet spectrum in heavy-ion collisions where the medium parameters are sampled from a realistic hydrodynamic evolution of the QGP. Up to relatively large radii R~0.6, the suppression is dominated by perturbative physics while non-perturbative effects, related to the details of thermalization, start to dominate at R~1. This provides, for the first time, a solid basis for higher-order precision calculations of the jet spectrum that are paramount to realize the potential of hard probes as precision tools to extract the properties of the QGP. However, jets are rare events and their spectrum drops rapidly with transverse momentum. This induces a strong bias on any process happening in the medium and makes it hard to dig out rare events where heavy-ion jets were substantially modified. In the second part of my talk, I will report on a recent attempt to extract the jet energy before quenching using machine learning. This allows to reduce the biases and enhance the signal of medium modifications. It also allows to better constrain jets as tomographic tools of the medium.

  28. High-Energy Physics & RIKEN Theory Seminar

    "Was There an Electroweak Phase Transition ?"

    Presented by Michael Ramsey-Musolf, U Mass, Amherst

    Thursday, February 18, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: Determining the thermal history of electroweak symmetry breaking (EWSB) is a key task for particle physics and cosmology. In the Standard Model, EWSB occurs via a crossover transition. In many scenarios for beyond the Standard Model (BSM) physics, however, the nature of the transition and pattern can differ, with important implications for baryogenesis and gravitational wave generation. I give generic arguments for why most BSM physics that leads to such an alternate history will be accessible at the LHC and next generation colliders. I also discuss recent developments in effective field theory and nonperturbative computations that are essential for a robust confrontation of theory with experiment.

  29. RIKEN seminar

    "Spectral functions from the real-time functional renormalization group"

    Presented by Philipp Scior, BNL

    Thursday, February 18, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Akio Tomiya

    Abstract: We employ the functional renormalization group approach formulated on the Schwinger-Keldysh contour to calculate real-time correlation functions in scalar field theories. We provide a detailed description of the formalism, discuss suitable truncation schemes for real-time calculations as well as the numerical procedure to self-consistently solve the flow equations for the spectral function. Subsequently, we discuss the relations to other perturbative and non-perturbative approaches to calculate spectral functions, and present a detailed comparison and benchmark in d=0+1dimensions.

  30. Nuclear Physics & RIKEN Theory Seminar

    "Two-baryon interactions from lattice QCD"

    Presented by Andrew Hanlon, BNL

    Friday, February 5, 2021, 9:15 am
    Videoconference / Virtual Event

    Hosted by: Semeon Valgushev

    Abstract: It has been over three decades since the first two-baryon studies from lattice QCD were performed. Despite algorithmic improvements and increases in computational resources since then, there remains disagreement on results from various groups in the lattice community. A major barrier in resolving these discrepancies is the poor signal-to-noise ratio for baryons, which needs to be overcome with modern methods. In this seminar, I will begin by covering various techniques and formalism that have become standard in lattice spectroscopy. This will include the use of distillation (and its stochastic variant) to treat all-to-all quark propagation; a variational method, which can help to reduce unwanted excited states while allowing for several desired states to be extracted; and the L\"uscher two-particle formalism, which relates finite-volume energies to infinite-volume scattering amplitudes. I will then present our recent results for two nucleon S-wave interactions in both isospin channels, computed at the SU(3)-flavor-symmetric point corresponding to mπ≈714 MeV. These results strongly disfavor the presence of any bound states at this pion mass, which contradicts some of the calculations in the literature. Further, our recent results for the H dibaryon—-also using an SU(3)-symmetric setup, but corresponding to mπ≈420 MeV—-show appreciable dependence on the lattice spacing. This could explain some of the discrepancies in the literature. However, I will discuss other possibilities, as well as future directions for spectroscopy.

  31. RIKEN seminar

    "A Triangle of Influence: Bringing Together Physics, Pure Mathematics, and Computer Science"

    Presented by James Halverson, Northeastern

    Thursday, February 4, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Akio Tomiya

    Abstract: Recent advances in machine learning have begun creating new bridges to physics and mathematics that have traditionally existed between the latter two. Given this progress, I will speculate about where we are and where things might be headed, including through the recently launched NSF AI Institute for Artificial Intelligence and Fundamental Interactions. Specifically, I'll survey well-known machine learning results in supervised learning, reinforcement learning, and generative models, and explain cases where these techniques are already impacting physics and math. In more detail, I will explain some remarkable similarities between neural networks and quantum field theory that might point towards a theoretical understanding of deep learning, and also how an AI agent's ability to unknot headphones might provide useful in cracking a foundational problem in topology.

  32. Nuclear Physics & RIKEN Theory Seminar

    "Gauge-invariant TMD factorization for Drell-Yan hadronic tensor at small x"

    Presented by Ian Balitsky, JLab/ODU

    Friday, January 29, 2021, 10 am
    Videoconference / Virtual Event

    Hosted by: Yacine Mehtar-Tani

    Abstract: The Drell-Yan hadronic tensor for electromagnetic (EM) current is calculated in the Sudakov region s»Q2»q2⊥ with 1Q2 accuracy, first at the tree level and then with the double-log accuracy. It is demonstrated that in the leading order in Nc the higher-twist quark-quark-gluon TMDs reduce to leading-twist TMDs due to QCD equation of motion. The resulting tensor for unpolarized hadrons is EM gauge-invariant and depends on two leading-twist TMDs: f1 responsible for total DY cross section, and Boer-Mulders function h⊥1. The order-of-magnitude estimates of angular distributions for DY process seem to agree with LHC results at corresponding kinematics.

  33. Nuclear Physics & RIKEN Theory Seminar

    "Effective Field theory for jet substructure in heavy ion collisions"

    Presented by Varun Vaidya, MIT

    Friday, January 22, 2021, 9 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    Abstract: I develop an Effective Field Theory (EFT) framework to compute jet substructure observables for heavy ion collision experiments. I consider dijet events that accompany the formation of a Quark Gluon Plasma(QGP) medium in a heavy ion collision and look at the simultaneous measurement of jet mass along with the transverse momentum imbalance between the jets accounting for both vacuum and medium evolution. Treating the energetic jet as an open quantum system interacting with a QGP bath, I write down a factorization formula within the SCET(Soft Collinear Effective Theory) framework for the reduced density matrix of the jet in the Markovian approximation. This allows a resummation of large logarithms that arise due to the final state measurements imposed while simultaneously summing over multiple interactions of the jet with the medium. I will discuss the novel IR structure of the medium modified jet function that arises in this factorization approach.

  34. High-Energy Physics & RIKEN Theory Seminar

    "EFT constraints from neutrino oscillation data"

    Presented by Martin Gonzalez-Alonso, University of Valencia

    Thursday, January 21, 2021, 11 am
    Videoconference / Virtual Event

    Hosted by: Julia Gehrlein

    Abstract: Neutrino oscillations are precision probes of new physics. Apart from neutrino masses and mixings, they are also sensitive to possible deviations of low-energy interactions between quarks and leptons from the Standard Model predictions. I will present a systematic description of such non-standard interactions (NSI) in oscillation experiments using an Effective Field Theory (EFT) approach. The relation with the traditional NSI formalism will be clarified. As a phenomenological example, I will discuss the application of this framework to short baseline reactor experiments such as Daya Bay. Bounds on operators of the Standard Model EFT will be extracted and compared with other probes.

  35. RIKEN seminar

    "Weak Value and CP Violation Measurement"

    Presented by Yuichiro Mori, KEK

    Thursday, January 21, 2021, 9 am
    Webcast

    Hosted by: Akio Tomiya

    Abstract: The weak value, proposed by Aharonov et al. in 1988, has been applied for various fields of physics for the purpose of precision measurement, which is made possible with the help of the 'postselection' specifying actively the final state in the physical process. Here we have considered the feasibility of applying the weak measurement in high energy particle physics, especially in measuring the CP-violating parameters in B meson decays, where the effective lifetime of the decay mode is expected to be prolonged statistically due to the postselection. Our analysis shows that, when adopted in the Belle II experiment at the SuperKEKB collider, the effective lifetime may be prolonged up to 2.6 times, and that the measurement precision of the CP-violating parameters may be improved by about 20%.

  36. RIKEN seminar

    "Correlated Dirac eigenvalues and axial anomaly in chiral symmetric QCD"

    Presented by Heng-Tong DING, Central China Normal University

    Thursday, January 14, 2021, 9 am
    https://bluejeans.com/871723105

    Hosted by: Akio Tomiya

    Abstract: How axial anomaly manifests itself in the two-point correlation functions of iso-triplet scalar and pseudo-scalar mesons affects the nature of chiral phase transition. In this talk we first review current status on the fate of UA(1) anomaly in the finite temperature lattice QCD, and then present a first continuum and chiral extrapolation of two UA(1) measures in (2+1)-flavor lattice QCD at 1.6Tc. After continuum and chiral extrapolations we find that axial anomaly remains manifested in the 2-point correlation functions of scalar and pseudo-scalar mesons in the chiral limit. To study the origin of the axial anomaly we propose novel relations between the quark mass derivatives of Dirac eigenvalue spectrum ρ and correlation functions among eigenvalues. We find that the peak structure developed in ρ in the infrared region with its height proportional to quark mass squared is responsible for the manifestation of axial anomaly. These findings suggest that the axial anomaly is driven by the weakly interacting (quasi-)instanton gas motived ρ at T>1.6Tc and the chiral phase transition belongs to 3-d O(4) universality class. The talk is based on https://arxiv.org/abs/2010.14836.

  37. Nuclear Physics & RIKEN Theory Seminar

    "Relativistic Navier-Stokes equations"

    Presented by Pavel Kovtun, University of Victoria

    Friday, January 8, 2021, 9 am
    https://bluejeans.com/362717467

    Hosted by: Semeon Valgushev

    Abstract: It has been widely believed that the relativistic Navier-Stokes equations violate the basic physical requirements of equilibrium stability and causality, and therefore can not be used for practical simulations of relativistic fluids. In this talk, I will discuss why this belief is unfounded. There is not one, but infinitely many Navier-Stokes equations because there are infinitely many conventions that can be used to define what one means by "fluid temperature", "fluid velocity" etc. out of equilibrium. The early works on relativistic hydrodynamics (Eckart, Landau-Lifshitz) have indeed adopted conventions that lead to unphysical predictions. On the other hand, when one adopts physically sensible conventions, the resulting relativistic Navier-Stokes equations are both stable and causal.

  38. RIKEN seminar

    "Toward full result for next-to-leading order dijet production in proton-nucleus collisions"

    Presented by Dr Yair Mulian, Jyvaskyla University

    Thursday, January 7, 2021, 9 am
    https://bluejeans.com/838379239

    Hosted by: Akio Tomiya

    Abstract: Using the CGC effective theory together with the hybrid factorisation, we study forward dijet production in proton-nucleus collisions beyond leading order. In this paper, we compute the "real" next-to-leading order (NLO) corrections, i.e. the radiative corrections associated with a three-parton final state, out of which only two are being measured. To that aim, we start by revisiting our previous results for the three-parton cross-section presented in our previous paper. After some reshuffling of terms, we deduce new expressions for these results, which not only look considerably simpler, but are also physically more transparent. We also correct several errors in this process. The real NLO corrections to inclusive dijet production are then obtained by integrating out the kinematics of any of the three final partons. We explicitly work out the interesting limits where the unmeasured parton is either a soft gluon, or the product of a collinear splitting. We find the expected results in both limits: the B-JIMWLK evolution of the leading-order dijet cross-section in the first case (soft gluon) and, respectively, the DGLAP evolution of the initial and final states in the second case (collinear splitting). The "virtual" NLO corrections to dijet production will be presented in a subsequent publication.

  39. Nuclear Physics & RIKEN Theory Seminar

    "Quarkyonic model for neutron stars"

    Presented by Srimoyee Sen, Iowa State University

    Friday, December 18, 2020, 9 am
    https://bluejeans.com/487211447

    Hosted by: Semeon Valgushev

    Abstract: The observed mass and radius relations of neutron stars can be explained remarkably well using a model of dense matter known as quarkyonic matter. I describe how the quarkyonic model can arise dynamically from an excluded volume model for nuclear interactions. I also discuss how thermal effects can be incorporated in such a model.

  40. RIKEN Seminar

    "Gluon imaging using azimuthal correlations in diffractive scattering at the Electron-Ion Collider"

    Presented by Mr Salazar Wong, Stony Brook University

    Thursday, December 17, 2020, 9 am
    https://bluejeans.com/871723105

    Hosted by: Akio Tomiya

    Abstract: Deeply virtual Compton scattering (DVCS) is a powerful channel to study the spatial structure of protons and nuclei at the future Electron-Ion Collider (EIC). In the collinear framework, DVCS is dependent on the quark and gluon generalized parton distributions (GPDs). At small x, these objects are closely related to the dipole correlator of Wilson Lines [1]. It is well known that the transverse momentum spectrum of DVCS at small x gives access to the impact parameter dependence of the dipole correlator. In [2], it was shown that by studying the azimuthal anisotropies of the final state photon with the electron plane in DIS one could also access the angular dependence of the dipole correlator. This information is crucial to unveil the structure of the orbital angular momentum carried by gluons inside hadrons and nuclei. In this talk, I will review the computation of DVCS at leading order in the CGC EFT, including the azimuthal angular correlations with respect to the electron plane. Then, I will show how to obtain similar expressions for exclusive vector meson production. I will then present our predictions for these anisotropies in electron-proton and electron-gold collisions for the kinematics of the future EIC. Finally, I will discuss the potential to measure the angular structure of color charge and geometric fluctuations in incoherent diffractive production. This talk is based on [3]. References: [1] Probing the Small-x Gluon Tomography in Correlated Hard Diffractive Dijet Production in DIS. arXiv:1601.01585 [2] Gluon Tomography from Deeply Virtual Compton Scattering at Small-x. Y. Hatta, B-W. Xiao, and F. Yuan. arXiv:1703.02085 [3] Gluon imaging using azimuthal correlations in diffractive scattering at the Electron-Ion Collider. H. Mäntysaari, K. Roy, F. Salazar, and B. Schenke. arXiv:2011.0246.

  41. Nuclear Physics & RIKEN Theory Seminar

    "Revealing the thermodynamics of strong interactions in ultrarelativistic heavy-ion collisions"

    Presented by Jean-Yves Ollitrault, IPhT/Saclay

    Friday, December 11, 2020, 9 am
    https://bluejeans.com/316945516

    Hosted by: Yacine Mehtar-Tani

    Collisions between heavy atomic nuclei at ultra-relativistic energies are carried out at particle colliders to produce a state of matter where quarks and gluons, the color degrees of freedom, are not bound - the quark–gluon plasma. This state is thought to be produced as a transient phenomenon before it fragments into thousands of particles that reach the particle detectors. I show how the thermodynamic properties of this transient state can be reconstructed from the information collected in detectors: The matter created in lead–lead collisions at the Large Hadron Collider at CERN is found to reach a temperature as high as 2.6 trillion degrees, the highest ever recorded in the laboratory. The value of the entropy density at this temperature, estimated from experimental data, agrees quantitatively with first-principles calculations from quantum chromodynamics. These results confirm that a deconfined phase of matter is indeed produced, in which sound waves propagate at half the speed of light.

  42. RIKEN Seminar

    "Study of axial U(1) anomaly at high temperature with lattice chiral fermions"

    Presented by Hidenori Fukaya, Osaka University

    Thursday, December 10, 2020, 9 am
    Videoconference / Virtual Event

    Hosted by: Akio Tomiya

    We investigate the axial U(1) anomaly of two-flavor QCD at temperatures 190–330 MeV. In order to preserve precise chiral symmetry on the lattice, we employ the M¨obius domain-wall fermion action as well as overlap fermion action implemented with a stochastic reweighting technique. Compared to our previous studies, we reduce the lattice spacing to 0.07 fm, simulate larger multiple volumes to estimate finite size effect, and take more than four quark mass points, including one below physical point to investigate the chiral limit. We measure the topological susceptibility, axial U(1) susceptibility, and examine the degeneracy of U(1) partners in meson and baryon correlators. All the data above the critical temperature indicate that the axial U(1) violation is consistent with zero within statistical errors. The quark mass dependence suggests disappearance of the U(1) anomaly at a rate comparable to that of the SU(2)L × SU(2)R symmetry breaking. This talk is based on a work in JLQCD collaboration, arXiv:2011.01499.

  43. Nuclear Physics & RIKEN Theory Seminar

    "Higgs-confinement phase transitions with fundamental representation matter"

    Presented by Aleksey Cherman, University of Minnesota Twin Cities

    Friday, December 4, 2020, 10 am
    Videoconference / Virtual Event

    Hosted by: Yacine Mehtar-Tani

    Abstract: I will discuss the conditions under which Higgs and confining regimes in gauge theories with fundamental representation matter fields can be sharply distinguished. It is widely believed that these regimes are smoothly connected unless they are distinguished by the realization of global symmetries. However, I will show that when a U(1) global symmetry is spontaneously broken in both the confining and Higgs regimes, the two phases can be separated by a phase boundary. The phase transition between the two regimes may be detected by a novel topological vortex order parameter. I'll illustrate these ideas by explicit calculations in gauge theories in three spacetime dimensions, and then explain the generalization to four dimensions. One important implication of our results is that nuclear matter and quark matter are sharply distinct phases of QCD with an approximate SU(3) flavor symmetry.

  44. RIKEN Seminar

    "Electroweak effective field theory from massive scattering amplitudes"

    Presented by Dr Teppei Kitahara, Nagoya University

    Thursday, December 3, 2020, 9 am
    Videoconference / Virtual Event

    Hosted by: Akio Tomiya

    The usual calculation method of field theory relies on Lagrangian under a certain symmetry. Then, one can obtain amplitudes by using Feynman rules and diagrams. In contrast, a method called "scattering amplitudes" (on-shell amplitudes, modern amplitude method, or spinor-helicity formalism) provides the amplitudes directly from symmetries without relying on Lagrangian. For example, a calculation of gluon n-point scattering amplitudes can be greatly reduced in this method. The scattering amplitude approach is expected to extract some essences in field theory, which are not obvious in the usual Feynman methods. Conventional scattering amplitude methods are the theory for massless particles, basically. In 2017, this method was generalized to involve massive particles by Nima Arkani-Hamed group. In this talk, first, I will provide a brief review of the scattering amplitudes. Next, I will introduce the scattering amplitude calculations connected with electroweak symmetry breaking, which are related to masses, vev, and longitudinal waves, by using the generalized method. In particular, we do not use Lagrangian. We derived (strictly speaking, re-derived) several equations for electroweak symmetry breaking that are supposed to be inherent in field theory. This talk is based on arXiv:1909.10551 and arXiv:2008.09652.

  45. Nuclear Physics & RIKEN Theory Seminar

    "Surprises in large Nc Thermodynamics"

    Presented by Thomas Cohen, Maryland U.

    Friday, November 20, 2020, 9 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    Abstract: This talk discusses some recent results in the thermodynamics of QCD in the limit where the number of colors,Nc, is large. It has long been known that there are very strong reasons to believe that large Nc QCD, unlike QCD with Nc=3, has a first order phase transition at zero chemical potential. This implies the existence of metastable superheated and supercooled regimes. Recently some remarkable properties of these phases have been elucidated, most dramatically the fact that the metastable supercoloed plasma phase at large Nc will have negative absolute pressure—a pressure below that of the vacuum.

  46. RIKEN Seminar

    "Correlated Dirac eigenvalues and axial anomaly in chiral symmetric QCD"

    Presented by Heng-Tong DING, Central China Normal University

    Thursday, November 19, 2020, 9 am
    Videoconference / Virtual Event

    Hosted by: Akio Tomiya

    Abstract: How axial anomaly manifests itself in the two-point correlation functions of iso-triplet scalar and pseudo-scalar mesons affects the nature of chiral phase transition. In this talk we first review current status on the fate of UA(1) anomaly in the finite temperature lattice QCD, and then present a first continuum and chiral extrapolation of two UA(1) measures in (2+1)-flavor lattice QCD at 1.6Tc. After continuum and chiral extrapolations we find that axial anomaly remains manifested in the 2-point correlation functions of scalar and pseudo-scalar mesons in the chiral limit. To study the origin of the axial anomaly we propose novel relations between the quark mass derivatives of Dirac eigenvalue spectrum ρ and correlation functions among eigenvalues. We find that the peak structure developed in ρ in the infrared region with its height proportional to quark mass squared is responsible for the manifestation of axial anomaly. These findings suggest that the axial anomaly is driven by the weakly interacting (quasi-)instanton gas motived ρ at T>1.6Tc and the chiral phase transition belongs to 3-d O(4) universality class. The talk is based on https://arxiv.org/abs/2010.14836.

  47. Nuclear Physics & RIKEN Theory Seminar

    "Heavy quark diffusion constant from the lattice"

    Presented by Viljami Leino, Munich Tech. U.

    Friday, November 13, 2020, 9 am
    Videoconference / Virtual Event

    Hosted by: Yoshitaka Hatta

    In this talk I will report our recent results on the computation of the heavy quark momentum diffusion coefficient from the correlator of two chromoelectric fields attached to a Polyakov loop in pure SU(3) gauge theory on lattice. We measured the diffusion coefficient on very wide range of temparatures from 1.1Tc to 10^4Tc. We see an agreement to perturbation theory at very high temperatures and can for the first time fit a temperature dependence of this quantity.

  48. Nuclear Physics & RIKEN Theory Seminar

    "Deterministic Fluctuating Hydrodynamics and Relativistic Heavy-Ion Collisions"

    Presented by Dr Xin An, North Carolina State University

    Friday, November 6, 2020, 9 am
    https://bluejeans.com/229416130

    Hosted by: Yoshitaka Hatta

    Abstract:Fluctuations are important measures in relativistic heavy-ion collisions, in particular near the QCD critical point. In this talk, I will discuss the state-of-the-art formalism for the deterministic fluctuating hydrodynamics, and connect it to the ongoing Beam Energy Scan Program at RHIC. I will also address recent progress in the dynamics of non-Gaussian fluctuations.

  49. RIKEN Seminar

    "Matter and radiation in the fragmentation region of heavy-ion collisions"

    Presented by Dr Isobel Kolbe, University of Washington

    Thursday, November 5, 2020, 11 am
    https://bluejeans.com/572844260

    Hosted by: Akio Tomiya

    Abstract: We study the fragmentation (far forward/backward) region of heavy-ion collisions by considering an at-rest nucleus which is struck by a relativistic sheet of colored glass. By means of a simple classical model, we calculate the subsequent evolution of baryons and the associated radiation. We confirm that the struck nucleus undergoes compression and that the dynamics of the early times of the collision are best described by two separate fluids as the produced radiation's velocity distribution is very different to the velocity distribution of the matter in the struck nucleus. (Based on https://arxiv.org/abs/2009.05680)

  50. NT/RIKEN seminar

    "Correlations, fluctuations and the QCD phase diagram"

    Presented by Volker Koch, LBNL

    Friday, October 23, 2020, 3:30 pm
    https://bluejeans.com/572303901

    Hosted by: Yoshitaka Hatta

    Abstract: I will discuss what we have so far learned about the QCD phase diagram by studying correlations and fluctuations. I will also address recent progress in relating lattice QCD results to actual measurements.

  51. NT/RIKEN seminar

    "The quest for explaining the top-row CKM unitarity deficit"

    Presented by Chien Yeah Seng, Bon

    Friday, October 16, 2020, 9 am
    https://bluejeans.com/534115036

    Hosted by: Yoshitaka Hatta

    Abstract: Symmetries of the weak sector of the Standard Model and its completeness find an exact mathematical realization in the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix. Of various relations among its elements, the top-row unitarity relation is by far the one known with the highest precision. The last few years have seen a rapid development in both the theory and experiments related to the extraction of the top-row CKM matrix elements and the respective unitarity relation, as quoted in the 2020 PDG: |V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=0.9985(3)_{V_{ud}}(4)_{V_{us}}. The apparent 3sigma deviation from unitarity points towards the possibility of BSM physics. Therefore, it is important to further reduce all the SM uncertainties in both V_{ud} and V_{us} in order to reach a level sufficient to claim a discovery. This involves a better understanding of various QCD matrix elements that enter the beta decays of neutron, nuclei and kaon, in particular those governing the electromagnetic radiative corrections (EMRC) in such processes. In this talk I will briefly describe the recent progress along this direction and discuss possible improvements in the future.

  52. NT/RIKEN seminar

    "Groomed and energy-energy correlation event shapes in DIS"

    Presented by Yiannis Makris, INFN, Pavia

    Friday, October 9, 2020, 9 am
    https://bluejeans.com/927877926

    Hosted by: Yacine Mehtar-Tani

    Abstract: With the future electron-ion collider data estimated to arrive in a decade, the need for theoretical and phenomenological tools to understand deep inelastic scattering (DIS) events has never been more urgent. In this seminar I will discuss early steps towards this direction. Specifically, I will focus on the adaptation to DIS of: i) the modified MassDrop Tagger grooming algorithm (mMDT) ii) and energy-energy correlation (EEC) event shape. Our adaptation relies on the geometrical separation of initial and final state radiation in the Breit frame, where I will establish the definitions of the proposed observables. The novel grooming procedure, although similar to mMDT, employs the Centauro measure used in the novel jet algorithm tailored to the needs of DIS. The groomed 1-jettiness will also be discussed.

  53. NT/RIKEN seminar

    "Quark matter cores in massive neutron stars"

    Presented by Aleksi Vuorinen, University of Helsinki

    Friday, October 2, 2020, 9 am
    https://bluejeans.com/572303901

    Hosted by: Semeon Valgushev

    Confirming or ruling out the existence of deconfined quark matter inside neutron stars is one of the most prominent open problems in nuclear astrophysics. While the ultimate goal continues to be the observation of a smoking gun signal directly indicating the presence or creation of quark matter, a more indirect approach to the problem has lately become feasible. By combining ab-initio theoretical results for the microscopic properties of dense QCD matter with the latest astrophysical measurements of neutron star properties, it is possible to build stringent model-independent constraints for the material properties of neutron-star matter at different densities. Presenting results from a very recent analysis of this kind, we argue that matter in the cores of the heaviest stable neutron stars has characteristics considerably closer to the predicted properties of deconfined quark matter than those of nuclear matter. The implications of this finding as well as potential ways of improving its accuracy are also discussed.

  54. NT/RIKEN seminar

    "New applications of dipole Monte Carlo implementations"

    Presented by Christian Bierlich, Lund University

    Friday, September 25, 2020, 9 am
    https://bluejeans.com/640344386

    Hosted by: Yoshitaka Hatta

    With data for small system collectivity getting ever more precise and diverse, and new experiments such as the EIC promise data with unprecedented geometric control, Monte Carlo generators face the requirement of a space-time picture of the initial state, to complement the more traditional momentum-space one. In this seminar I will present how the Muller dipole model has been used to that effect, previously in the DIPSY event generator, and is now being used in PYTHIA as well. Since all parameters of the model can be fitted to inclusive quantities, it offers a solid starting point for such efforts. Furthermore, since the model calculates projectile and target Fock states event-by-event, color fluctuations of the nucleon-nucleon, or γ*-nucleon, cross-section comes about as a by-product. Finally, once there is an initial space-time structure, a mechanism is needed to transport initial state anisotropies to the final state. Over the past years we have developed a model based on interacting strings, with exactly this aim. I will discuss recent developments, with a focus on response to initial state geometry, and similarities to hydro.

  55. NT/RIKEN seminar

    "Loop, String, and Hadron Dynamics in SU(2) Hamiltonian Lattice Gauge Theories"

    Presented by Dr Jesse Stryker, U. Washington

    Friday, September 18, 2020, 11 am
    https://bluejeans.com/273012913

    Hosted by: Yoshitaka Hatta

    We present a reformulation of an SU(2) Hamiltonian lattice gauge theory—-a loop-string-hadron (LSH) formulation—-that characterizes dynamics directly in terms of its loop, string, and hadronic degrees of freedom, while alleviating several apparent disadvantages of quantumly simulating the Kogut-Susskind formulation. This LSH formulation, derived from Schwinger bosons, extends the local loop formulation of (d+1)-dimensional lattice gauge theories by incorporating staggered quarks, furnishing the algebra of gauge-singlet operators, and succinctly encoding the dynamics among states having Gauss's law built in to them. LSH operators are factored into explicit products of "normalized'' ladder operators and diagonal matrices, priming them for applications in quantum algorithms. Self-contained translations of the Hamiltonian are given and I comment on the next steps for this framework.

  56. NT/RIKEN Seminar

    "On next to soft corrections to Inclusive cross sections at the colliders"

    Presented by Vajravelu Ravindran

    Friday, September 11, 2020, 9 am
    https://bluejeans.com/849527782

    Hosted by: Yoshitaka Hatta

    We present [hep-ph/2006.06726] a framework that resums threshold enhanced large logarithms to all orders in perturbation theory for inclusive processes such as the production of a pair of leptons in Drell-Yan process and of Higgs boson in gluon fusion as well as in bottom quark annihilation at the hadron colliders. In addition, we apply [hep-ph/2007.12214] this to Deep Inelastic Scattering (DIS) and hadron production in Semi-Inclusive Annihilation (SIA) of electron positron colliders. These logarithms include the distributions P(log?^i (1−z))/1−z)) resulting from soft plus virtual (SV) and the logarithms log?^i (1−z) from next to SV contributions. We use collinear factorisation and renormalisation group invariance to achieve this. We find that the resummed result is a solution to Sudakov type differential equation and hence it can predict soft plus virtual contributions as well as next to SV contributions to all orders in strong coupling constant to the partonic coefficient function in terms of infrared anomalous dimensions and process independent functions. The z space resummed result is shown to have integral representation which allows us to resum the large logarithms of the form log?i(N) retaining 1/N corrections resulting from next to SV terms. We show that in N space, tower of logarithms are summed to all orders in strong coupling constant.

  57. NT/RIKEN seminar

    "The Curious Story of the Photon"

    Presented by Bowen Xiao, CCNU

    Friday, September 4, 2020, 9 am
    Webcast

    Hosted by: Yoshitaka Hatta

    In this talk, I will talk about several interesting and peculiar aspects of the photon in high energy scatterings. First, I will review the history of Weizsacker-Williams photon distribution in a relativistic moving charged particle in the so-called equivalent photon approximation (EPA), and discuss the extension of this method towards the photon Wigner distribution. These methods can be applied to the dilepton productions recently measured by STAR, ATLAS and CMS collaborations. In the end, I will also mention the rich QCD structure of the photon and its implication on the collective phenomenon at the future EIC. https://bluejeans.com/429607848

  58. virtual NT/RIKEN seminar

    "Does eta/s depend on EoS?"

    Presented by Pasi Huovinen, Institute of Physics Belgrade

    Friday, August 28, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    Extracting the shear viscosity of quark-gluon plasma from experimental data has been one of the major goals of heavy-ion physics, leading to very low values of eta/s = 1-2/4pi. Most of these works have been done using by now outdated EoS parametrization, and I'll discuss how and whether the use of contemporary EoS affects the extracted EoS in a full-fledged Bayesian analysis. I will also discuss whether the minimum value of eta/s depends on how the temperature dependence of eta/s is parametrised. bluejeans: https://bluejeans.com/826383959

  59. virtual NT/RIKEN seminar

    "Strongly coupled QFT dynamics via TQFT coupling"

    Presented by Mithat Unsal, NCSU

    Friday, August 21, 2020, 9 am
    https://bnl.bluejeans.com/726276981

    Hosted by: Nikhil Karthik

    We consider a class of quantum field theories and quantum mechanics, which we couple to topological QFTs, in order to classify non-perturbative effects in the original theory. The TQFT structure arises naturally from turning on a classical background field for a discrete 0- or 1-form global symmetry present in the theory. By using this method, I prove that the the non-perturbative expansion parameter is exp[-S_I/N]= \exp[-{8 \pi^2}/{g^2N}], both in the semi-classical weak coupling domain and strong coupling domain, corresponding to a fractional topological charge configurations. To classify the non-perturbative effects in original SU(N) theory, we must use PSU(N) bundle and lift configurations (critical points at infinity) for which there is no obstruction back to SU(N). These provide a refinement of instanton sums: integer topological charge, but crucially fractional action configurations contribute.

  60. RIKEN Seminar

    "Quarkonium production and polarization in the color evaporation model"

    Presented by Vincent Cheung, UC Davis

    Thursday, August 13, 2020, 9 am
    https://bluejeans.com/732452652

    Hosted by: Yuta Kikuchi

    Quarkonium production and polarization in the color evaporation model Abstract: One of the best ways to understand hadronization in QCD is to study the production of quarkonium. The color evaporation model (CEM) and Nonrelativistic QCD (NRQCD) can describe production yields rather well but spin-related measurements like the polarization are stronger tests. In this talk, I will outline the quarkonium polarization puzzle and present recent attempts to use the color evaporation model to describe the polarization of quarkonium production.

  61. virtual NT/RIKEN seminar

    "Conserved charges in general relativity and its implication on Oppenheimer-Volkoff equation"

    Presented by Sinya Aoki, YITP, Kyoto

    Friday, August 7, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    We present a precise definition of a conserved quantity from an arbitrary covariantly conserved current available in a general curved spacetime. This definition enables us to define energy and momentum for matter by the volume integral. As a result we can compute charges of well-known black holes just as an electric charge of an electron in electromagnetism by the volume integration of a delta function singularity. As a byproduct we show that the definition leads to a correction to the known mass formula of a compact star in the Oppenheimer-Volkoff equation. Bluejeans link: https://bnl.bluejeans.com/726276981

  62. virtual NT/RIKEN seminar

    "QCD factorization and resummation in the small-x regime"

    Presented by Zhangbo Kang, UCLA

    Friday, July 31, 2020, 11 am
    https://bnl.bluejeans.com/726276981

    Hosted by: Nikhil Karthik

    The physics of gluon saturation or color glass condensate (CGC) has been one of the main driving forces for the future Electron Ion Collider. Significant progress has been made in the theory and phenomenology for computing physics observables measured at RHIC and LHC in the past decades. However, the higher-order perturbative calculations in the CGC formalism still remains a bit elusive, especially in comparison with the conventional QCD collinear factorization in the dilute regime. In this talk, using single hadron production in proton-nucleus collisions as an example, I point out some of the interesting difficulties and demonstrate how this can be solved. For example, in the standard collinear factorization, the natural hard scale will automatically arise from a higher-order calculation, while choosing the natural rapidity scale for small-x remains quite tricky even with explicit higher-order calculation. I further show how to perform threshold resummation and demonstrate how this would solve the well-known negative cross section problem for this process.

  63. RIKEN Seminar

    "Massive Thirring model in 1+1 dimensions from matrix product states"

    Presented by C.-J. David Lin, National Chiao-Tung University, Taiwan

    Thursday, July 30, 2020, 9 am
    Webcast

    Hosted by: Akio Tomiya

    The method of matrix product states (MPS), as one of the tensor-network (TN) approaches, has been shown to be applicable to study 1+1 dimensional quantum field theories in the canonical formalism. In this talk, I present our work on the massive Thirring model using the MPS technique. Our work shows that the MPS method can be used to identify a Berezinskii-Kosterlitz-Thouless phase transition in the Thirring model. I will also discuss our exploratory results for real-time dynamics and dynamical phase transition. BJ link https://bluejeans.com/871723105

  64. virtual NT/RIKEN seminar

    "Universal location of the Yang-Lee edge singularity in O(N) theories"

    Presented by Gregory Johnson, NCSU

    Friday, July 24, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    We determine a previously unknown universal quantity, the location of the Yang-Lee edge singularity for the O(N) theories in a wide range of N and various dimensions. At large N, we reproduce the N\to\infty analytical result on the location of the singularity and, additionally, we obtain the mean-field result for the location in d=4 dimensions. In order to capture the nonperturbative physics for arbitrary N, d and complex-valued external fields, we use the functional renormalization group approach. Bluejeans link: https://bnl.bluejeans.com/726276981

  65. RIKEN Seminar

    "Parton Distribution Functions inside Hardron from lattice QCD"

    Presented by Xiang Gao, BNL

    Thursday, July 23, 2020, 9 am
    Webcast

    Hosted by: Yuta Kikuchi

    Due to the light-cone separation, straightforward calculation of Patron Distribution Function (PDF) is not possible using lattice QCD. The Large Momentum Effective Theory (LaMET) provides a systematic way to relate the quasi-PDF, defined by equal-time correlators at large hadron momentum state, to the PDF order by order in perturbation theory. Within the framework of LaMET, we study the pion valence PDF and the nucleon iso-vector PDFs. Our analysis use both RI-MOM and ratio-based schemes to renormalize the quasi-PDF matrix elements. We reconstruct the x-dependent, as well as infer the first few moments of the pion valence PDF. We compare nucleon iso-vector quasi-PDF matrix elements with the corresponding results of the global fits in coordinate space.

  66. virtual NT/RIKEN seminar

    "Probing Gluon Sivers Function in J/psi production at the Electron-Ion Collider"

    Presented by Asmita Mukherjee, IIT Bombay

    Friday, July 17, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    Bluejeans link: https://bnl.bluejeans.com/726276981

  67. virtual NT/RIKEN seminar

    "Transverse momentum broadening in the Glasma"

    Presented by Andreas Ipp, TU Wien

    Friday, July 10, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    Jets are hard probes that originate from initial hard scatterings of the nuclei in heavy ion collisions. They acquire transverse momentum broadening through interaction with the evolving quark-gluon plasma. However, already the pre-equilibrium Glasma stage can contribute to transverse momentum broadening. In this talk, I present our recent work [1] where we calculate the contribution to transverse momentum broadening from the Glasma phase. We base our calculation on the boost-invariant 2+1D Glasma description which builds upon the Color Glass Condensate framework. Interestingly, we find strong time-dependence and anisotropic results with larger momentum broadening in the direction along the beam axis. [1] https://arxiv.org/abs/2001.10001 Bluejeans link: https://bnl.bluejeans.com/726276981

  68. virtual NT/RIKEN seminar

    "Postmerger gravitational-wave signatures of phase transitions in binary mergers"

    Presented by Lukas Weih, ITP Frankurt

    Friday, June 26, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    With the first detection of gravitational waves from a binary system of neutron stars, GW170817, a new window was opened to study the properties of matter at and above nuclear-saturation density. Reaching densities a few times that of nuclear matter and temperatures up to 100 MeV, such mergers represent potential sites for a phase transition from confined hadronic to deconfined quark matter. While for GW170817 the postmerger signal could not be detected, such a signal will be a powerful observable in the near future. In this seminar I will present the possible scenarios of how a phase transition to quark-gluon plasma can take place in the postmerger phase of a binary neutron star merger. I will focus on the most recently explored scenario of a so-called ``delayed phase transition'', where the merger remnant transitions from a purely hadronic hypermassive neutron star to a meta-stable hypermassive hybrid star with a dense quark core. This process promises to yield the strongest signature in the gravitational-wave signal for the production of quark matter in the present Universe. Bluejeans link: https://bnl.bluejeans.com/726276981

  69. RIKEN Seminar

    "Nonperturbative quark-flavor breaking at chiral crossover criticality in hot QCD"

    Presented by Mamiya Kawaguchi, Fudan University

    Thursday, June 25, 2020, 9 am
    Webcast

    Hosted by: Akio Tomiya

    We discuss the violation of quark-flavor symmetry at high temperatures, induced from axial anomaly and nonperturbative thermal loop corrections. To perform the nonperturbative analysis, we employ a three-flavor linear-sigma model based on the Cornwall-Jackiw-Tomboulis formalism, in which the flavor breaking induced by the axial anomaly plays a significant role in the light scalar meson spectrum and the vacuum structure of the chiral symmetry. In this talk, we will show the flavor breaking effects on the quark condensates and the meson spectroscopy. The critical flavor violation in the topological susceptibility will be also presented. BJ link: https://bluejeans.com/871723105

  70. virtual NT/RIKEN seminar

    "Prompt, pre-equilibrium, and thermal photons in relativistic nuclear collisions"

    Presented by Akihiko Monnai, JWU Tokyo

    Friday, June 19, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    The direct photon emission model in relativistic nuclear colliders has been improved in recent years for reducing the discrepancy between theoretical estimations and experimental data and for understanding the properties of the QCD matter. In this talk, the contribution of pre-equilibrium photons are investigated in addition to those of prompt and thermal photons in the framework of a relativistic hydrodynamic model. The numerical simulations at an LHC energy suggest that the pre-equilibrium photons may be relevant at intermediate transverse momentum near the saturation momentum scale, increasing particle spectra and reducing elliptic flow of direct photons. Bluejeans link: https://bnl.bluejeans.com/726276981

  71. RIKEN Seminar

    "Deep learning black hole metrics from shear viscosity"

    Presented by Prof. Shao-Feng Wu, Hanghai University, Yangzhou University

    Thursday, June 18, 2020, 9 am
    https://bluejeans.com/871723105

    Hosted by: Nikhil Karthik

    Based on the AdS/CFT correspondence, we build up a simple deep neural network to learn the black-hole metrics from the complex frequency-dependent shear viscosity. The network architecture provides a discretized representation of the holographic renormalization group flow of the shear viscosity and is applicable for a large class of strongly coupled field theories. Given the existence of the horizon and guided by the smoothness of spacetimes, we show that the Schwarzschild and Reissner-Nordstrom metrics can be learned accurately. Moreover, we illustrate that the generalization ability of the deep neural network can be excellent, which indicates that using the black hole spacetime as a hidden data structure, a wide spectrum of the shear viscosity can be generated from a narrow frequency range. Our work might not only suggest a data-driven way to study holographic transports, but also shed new light on the emergence mechanism of black hole spacetimes from field theories.

  72. virtual NT/RIKEN seminar

    "The quest for precision across scales"

    Presented by Gregory Soyez, IPhT

    Friday, June 12, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    Monte Carlo event generators are among the most used tools in high-energy physics today. As an introduction, I will explain what is their role in modern collider phenomenology. The talk will focus on a central part of Monte Carlo generators, the parton shower, which essentially covers all the scales between the hard scale of the collision and the non-perturbative scale. I will describe how typical parton-shower algorithms are built. I will then report on a recent work (arXiv:2020:11114) where we introduced a new set of parton showers aimed at achieving an unprecedented (logarithmic) accuracy. https://bnl.bluejeans.com/726276981

  73. RIKEN Seminar

    "Transport and hydrodynamics in the chiral limit"

    Presented by Alexander Soloviev, Stony Brook University

    Thursday, June 11, 2020, 9 am
    Webcast

    Hosted by: Yuta Kikuchi

    I will discuss the evolution of hydrodynamic fluctuations for QCD matter below T_c in the chiral limit. The theoretical description is ordinary hydrodynamics at long distances and superfluid-like at short distances. The latter is represented by pions (the Goldstone modes), reflecting the broken SU(2)_L x SU(2)_R symmetry. The superfluid degrees of freedom contribute to the transport coefficients of the ordinary theory at long distances. This determines the leading dependence of some transport parameters of QCD on the pion mass. I will make some comments on the predictions of this computation near the O(4) critical point. https://bluejeans.com/724325293

  74. RIKEN Seminar

    "From quarks to nuclei: machine learning the structure of matter"

    Presented by Phiala Shanahan, MIT

    Thursday, June 4, 2020, 12 pm
    Webcast

    Hosted by: Akio Tomiya

    I will discuss the status and future of lattice Quantum Chromodynamics (QCD) calculations for nuclear physics. With advances in supercomputing, we are beginning to quantitatively understand nuclear structure and interactions directly from the fundamental quark and gluon degrees of freedom of the Standard Model. Recent studies provide insight into the neutrino-nucleus interactions relevant to long-baseline neutrino experiments, double beta decay, and nuclear sigma terms needed for theory predictions of dark matter cross-sections at underground detectors. The rapid progress in this field has been possible because of new algorithms but challenges still remain to reach the large nuclei used in many of these experiments. Recently, machine learning tools have been shown to provide a potentially revolutionary way to address these challenges and allow a Standard Model understanding of the physics of nuclei. Bluejeans link: https://bluejeans.com/806818825

  75. virtual NT/RIKEN seminar

    "First-principles calculation of electroweak box diagrams from lattice QCD"

    Presented by Luchang Jin, U. Conn

    Friday, May 29, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    Bluejeans link: https://bnl.bluejeans.com/726276981

  76. Virtual BNL RIKEN Seminar

    "Sign Problem in Monte Carlo Simulations and the Tempered Lefschetz Thimble Method"

    Presented by Masafumi Fukuma, Kyoto U.

    Thursday, May 28, 2020, 9 am
    Webcast

    Hosted by: Akio Tomiya

    The tempered Lefschetz thimble method (TLTM) [arXiv:1703.00861] is a parallel-tempering algorithm towards solving the numerical sign problem. It uses the deformation parameter of integration surface (the flow time of the antiholomorphic gradient flow) as a tempering parameter, and is expected to tame both the sign and ergodicity problems simultaneously that exist intrinsically in thimble methods. In this talk, I explain the basics of TLTM, and apply the method to various problems, including the quantum Monte Carlo simulation of the Hubbard model away from half filling and the chiral random matrix models with finite temperature and finite chemical potential. This talk is based on collaboration with Nobuyuki Matsumoto and Naoya Umeda [arXiv: 1703.00861, 1906.04243, 1912.13303]. Bluejeans Link: https://bluejeans.com/871723105

  77. virtual NT/RIKEN seminar

    "Why is chemical freezeout at the chiral cross over temperature?"

    Presented by Sourendu Gupta, TIFR Mumbai

    Friday, May 22, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    Studies of the composition of the fireball produced in very high energy heavy-ion collisions show that the composition is that of an equilibrium gas of hadrons at a temperature of about 155 MeV, and zero chemical potential. At the same time, lattice computations show that the chiral cross over of QCD occurs at a temperature of about 155 MeV. The composition of the fireball is a question of the dynamics of hadron reactions, whereas the location of a cross over is a question about the equilibrium free energy density. I describe a computation which shows why they coincide. Bluejeans link: https://bnl.bluejeans.com/726276981

  78. RIKEN Seminar

    "From anomalous correlations to dark matter: the effects of higher topological charge"

    Presented by Fabian Rennecke, BNL

    Thursday, May 21, 2020, 9 am
    Bluejeans link: https://bluejeans.com/651508428

    Hosted by: Yuta Kikuchi

    Topological gauge field configurations play an important role in the phenomenology of QCD. The axial anomaly is inextricably linked to topological effects. They give rise to anomalous meson masses, affect the order of the chiral phase transition, and lead to the chiral magnetic effect which is relevant for condensed matter and heavy-ion physics. On the flip side, topological gauge field configurations can also give rise to CP violating effects in QCD. A potential resolution of this strong CP problem involves a new particle, the axion. Incidentally, axions are also viable dark matter candidates and their properties are largely determined by the distribution of topological charge in QCD. At high energies in the deconfined regime, the topological structure of QCD is well described by a dilute gas of instantons. In this regime all the effects mentioned above are typically studied based on instantons of unit topological charge. As discussed in this talk, there are also effects uniquely related to instantons of higher topological charge. On the one hand, they give rise to higher-order anomalous quark correlations which manifest themselves in anomalous hadronic interactions. On the other hand, they modify the distribution of topological charge. This, in turn, affects the properties of axions and can lead to a topological mechanism to increase the amount of axion dark matter.

  79. virtual NT/RIKEN seminar

    "Quantum criticality in fermion-bag inspired Hamiltonian lattice field theories"

    Presented by Emilie Huffman, Perimeter Institute

    Friday, May 15, 2020, 11 am
    Webcast

    Hosted by: Nikhil Karthik

    Motivated by the fermion bag approach—a quantum Monte Carlo approach that takes advantage of grouped local degrees of freedom—we consider a new class of Hamiltonian lattice field theories that can help us study fermionic quantum critical points. We construct the partition function of a lattice Hamiltonian in 2+1 dimensions in discrete time, with a temporal lattice spacing \varepsilon. When \varepsilon \rightarrow 0, we obtain the partition function of the original lattice Hamiltonian. But when \varepsilon = 1, we obtain a new type of space-time lattice field theory which treats space and time differently, but still lacks fermion doubling in the time dimension, in contrast to Lagrangian lattice field theories. Here we show that both continuous-time and discrete-time lattice field theories derived from the t-V model have a fermionic quantum critical point with critical exponents that match within errors. The fermion bag algorithms run relatively faster on the discrete-time model and allow us to compute quantities even on 100^3 lattices near the quantum critical point. Bluejeans link: https://bnl.bluejeans.com/726276981

  80. virtual NT/RIKEN seminar

    "Open QFTs from holography"

    Presented by R. Loganayagam, ICTS, Bangalore

    Friday, May 8, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    In this talk, I will outline a formalism to study open quantum field theories using holographic methods. More precisely, I will consider a quantum field theory (the system) coupled to a holographic field theory at finite temperature (the environment). The aim here is to integrate out the holographic environment with an aim of obtaining an effective dynamics for the resulting open quantum field theory. This is done using semiclassical gravitational Schwinger-Keldysh saddle geometries obtained by complexifying black hole spacetimes. In addition to shedding light on open quantum systems coupled to strongly correlated thermal environments, these results also provide a principled computation of Schwinger-Keldysh observables in gravity and holography. In particular, these influence functionals capture both the dissipative physics of black hole quasinormal modes, as well as that of the fluctuations encoded in outgoing Hawking quanta, and interactions between them. This talk will be based on https://arxiv.org/abs/2004.02888 Bluejeans link: https://bnl.bluejeans.com/726276981

  81. virtual NT/RIKEN seminar

    "Transverse momentum distributions: predictive power and flavor structure"

    Presented by Andrea Signori, Jlab

    Friday, May 1, 2020, 9 am
    Webcast

    Hosted by: Nikhil Karthik

    Transverse momentum distributions (TMDs) allow one to map the hadronic structure in a three-dimensional momentum space, exploring all the possible spin and momentum correlations between a hadron and its elementary constituents. I will discuss their predictive power as a function of the kinematics and, in particular, I will show that the flavor structure of the TMDs can have an impact on the determination of the W boson mass at the Large Hadron Collider, providing a new connection between 3D hadron tomography and high-energy physics. Bluejeans link: https://bnl.bluejeans.com/726276981

  82. virtual NT/RIKEN seminar

    "3D Tomography of Parton Motion inside Hadrons"

    Presented by Jianwei Qiu, Jefferson Lab

    Friday, April 24, 2020, 9 am
    Bluejeans: https://bnl.bluejeans.com/726276981

    Hosted by: Nikhil Karthik

    The TMD Topical Collaboration, funded by the DOE Office of Nuclear Physics, was formed by pulling together expertise in QCD theory, phenomenology and lattice QCD from 10 universities and 4 national labs to address the challenge to develop new theoretical and phenomenological tools that are urgently needed for precision extraction of 3D tomography of parton motion inside hadrons from current and future data. In this talk, I will briefly summarize the challenge to extract the true parton motion inside a bound hadron once it is broken by the collisions, and how the TMD Collaboration integrates our knowledge in QCD theory, phenomenology and lattice QCD to overcome the challenge.

  83. Virtual NT/RIKEN seminar

    "Exploring aspects of QCD from Quantum Link Models"

    Presented by Debasish Banerjee, PNNL

    Friday, April 17, 2020, 9 am
    Bluejeans:https://bnl.bluejeans.com/726276981

    Hosted by: Nikhil Karthik

    QCD has been extensively studied in various regimes and using various methodologies. While the lattice regularized version is the most popular ab-initio version, this approach has problems dealing with dense, as well as non-equilibrium QCD matter. In this talk, I will introduce the so-called Quantum Link Models, which offer a different approach to the problem. We will explore some qualitative aspects of QCD and nuclear physics using these models.

  84. NT/RIKEN Seminar

    "A mode by mode approach to heavy ion collision"

    Presented by Eduardo Grossi, SBU

    Friday, April 10, 2020, 9 am
    Bluejeans: https://bnl.bluejeans.com/726276981

    Hosted by: Nikhil Karthik

  85. NT/RIKEN Seminar- CANCELLED

    "A mode by mode approach to heavy ion collision"

    Presented by Eduardo Grossi, SBU

    Friday, March 13, 2020, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Nikhil Karthik

  86. RIKEN Lunch Seminar

    "Ioffe time behavior of PDFs and GPDs"

    Presented by Abha Rajan, BNL

    Thursday, March 12, 2020, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    Ioffe time essentially quantifies the distance along the lightcone that the quark fields that enter the correlator describing the Parton Distribution Function (PDF) are separated by. In this sense, it is a natural candidate for clearly separating the short and long distance physics. We study how the behavior of the parton distribution in Ioffe time can be mapped out given its Mellin moments. Pseudo PDFs describe the nucleon matrix elements of quark field operators separated by a space like distance z. These are calculable in lattice QCD and as z^2 approaches zero, pseudo PDFs approach the actual PDFs. Complimentary to lattice efforts, we study the behavior of of pseudo PDFs as a function of z in a spectator diquark model. We also extend the study to Generalized Parton Distributions (GPDs), which involves taking into account an extra degree of freedom because of the non diagonal nature of the hadronic matrix element in the case of GPDs.

  87. RIKEN Lunch Seminar

    "Nonperturbative Collins-Soper Kernel from Lattice QCD"

    Presented by Yong Zhao, BNL

    Thursday, March 5, 2020, 12 pm
    Building 510, Room 2-160

    Hosted by: Akio Tomiya

    The transverse momentum dependent parton distribution functions (TMDPDFs) measure the transverse momentum of partons in a fast moving hadron, and is an important observable for the Electron-Ion Collider. The energy evolution of TMDPDFs is given by the Collins-Soper (CS) anomalous dimension, or the CS kernel, which is essential to the fitting of TMDPDFs from global cross section data at different energies. At small transverse momentum, the CS kernel is nonperturbative and can only be determined from global fitting or first principle calculations. In this talk, I present an exploratory calculation of the CS kernel from lattice QCD using the large-momentum effective theory, which is a systematic approach to extract light-cone parton physics. Our preliminary results show that it is promising to achieve precision calculation with currently available computing resources, which has the potential to be used in the global fitting of TMDPDFs in the future.

  88. NT/RIKEN Seminar

    "Studying supranuclear matter with gravitational waves from neutron star binaries"

    Presented by Katerina Chatziioannou

    Friday, February 28, 2020, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

  89. NT/RIKEN Seminar

    "Soft Fragmentation on the Celestial Sphere"

    Presented by Duff Neill

    Friday, February 21, 2020, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Nikhil Karthik

    We develop two approaches to the problem of soft fragmentation of hadrons in a gauge theory for high energy processes. The first approach directly adapts the standard resummation of the parton distribution function's anomalous dimension (that of twist-two local operators) in the forward scattering regime, using kT-factorization and BFKL theory, to the case of fragmentation function by exploiting the mapping between the dynamics of eikonal lines on transverse-plane to the celestial-sphere. Critically, to correctly resum the anomalous dimension of the fragmentation function under this mapping, one must pay careful attention to the role of regularization, despite the manifest collinear or infra- red finiteness of the BFKL equation. The anomalous dependence on energy in the celestial case, arising due to the mismatch of dimensionality between positions and angles, drives the differences between the space-like and time-like anomalous dimension of parton densities, even in a conformal theory. The second approach adapts an angular-ordered evolution equation, but working in 4 − 2epsilon dimensions at all angles. The two approaches are united by demanding that the anomalous dimension in 4 − 2epsilon dimensions for the PDF determines the kernel for the angular-ordered evolution to all orders.

  90. RIKEN Lunch Seminar

    "Phase Transitions of Quantum Annealing and Quantum Chaos"

    Presented by Dr Kazuki Ikeda, Osaka University

    Thursday, February 20, 2020, 12 pm
    Building 510, Room 1-224

    Hosted by: Akio Tomiya

    It is known that quantum phase transitions occur in the process of quantum annealing. The order of phase transition and computational efficiency are closely related with each other. Quantum computation starts with a non-entangled state and evolves into some entangled states, due to many body interactions and the dynamical delocalization of quantum information over an entire system's degrees of freedom (information scrambling). It is common to diagnose scrambling by observing the time evolution of single qubit Pauli operators with an out-of-timeorder correlator (OTOC). We aim at establishing a method to clarify those relations between phase transitions and scrambling by OTOCs. Using the p-spin model, we diagnose quantum phase transitions associated with quantum annealing and reverse annealing. In addition we provide a novel Majorana fermion model in which non-stoquastic dynamics of annealing can turn a first-order phase transition into a second-order phase transition. We also show that these phase transitions can be diagnosed by the OTOCs.

  91. Special NT/RIKEN Seminar

    "Infrared gluon mass and the Gribov-Zwanziger model of nonperturbative Yang-Mills theories"

    Presented by Leticia Palhares

    Wednesday, February 19, 2020, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Nikhil Karthik

    In this talk we review indications of an infrared gluon mass in different nonperturbative approaches and discuss its dynamical generation in a Gribov-Zwanziger model. We compute in particular the one-loop effective potential of the model in the recently-established BRST-invariant setup which guarantees gauge-parameter independence of the generated mass scales.

  92. Special NT/RIKEN Seminar

    "Critical dynamics from small, noisy, fluctuating systems"

    Presented by Eduardo Fraga

    Tuesday, February 18, 2020, 1 pm
    Building 510, CFNS Room 2-38

    Hosted by: Nikhil Karthik

    Current heavy-ion collision experiments might lead to the discovery of a first-order chiral symmetry breaking phase-transition line, ending in a second-order critical point. Nevertheless, the extraction of information about the equilibrium thermodynamic properties of baryonic matter from the highly dynamic, small, noisy and fluctuating environment formed in such collisions is an extremely challenging task. We address some of the limitations present in the experimental search for the QCD critical point.

  93. NT/RIKEN Seminar

    "Solving the medium-induced gluon radiation spectrum for an arbitrary number of scatterings"

    Presented by Carlota Andres Casas

    Friday, February 14, 2020, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

    New measurements of jet quenching observables at RHIC and at the LHC, such as jet substructure observables, demand an increased precision in the theory calculations describing medium-induced radiation of gluons. Closed expressions for the gluon spectrum including an arbitrary number of multiple scatterings have been known for the past 20 years, but analytical calculations have failed to evaluate this spectrum using realistic models for parton-medium interactions. We show a flexible method which allows us to write the analytical expressions for the full in-medium spectrum, including the resummation of all multiple scatterings, in a form where the numerical evaluation can be easily performed without the need of the usually employed harmonic or first opacity approximation. We present the transverse momentum and energy-dependent medium-induced gluon emission distributions for known realistic interaction models to illustrate how our framework can be applied beyond the limited kinematic regions of previous calculations.

  94. RIKEN Lunch Seminar

    "Shedding light on photon and dilepton spectral functions"

    Presented by Greg Jackson, University of Bern

    Thursday, February 13, 2020, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    Photons and dileptons offer themselves as 'clean' probes of the quark-gluon plasma because they are unlikely to reinteract once produced. Their emission rates are given via the vector channel spectral function, an object that can ultimately be reconstructed by analytic continuation of lattice data. To confront perturbative results with that data, the NLO corrections are needed in all domains that affect the associated imaginary-time correlator, namely for energies above, below and in the vicinity of the light cone. We summarize recent progress here and, to control an unavoidable snag, we also determine these corrections for the transverse and longitudinal polarizations separately. Our results should help to scrutinize direct spectral reconstruction attempts from lattice QCD.

  95. Special NT/RIKEN Seminar

    "Partonic structure of the proton from large momentum effective theory"

    Presented by Xiangdong Ji

    Monday, February 10, 2020, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Nikhil Karthik

  96. NT/RIKEN Seminar

    "New tools for the quantum many-body problem"

    Presented by Dean Lee

    Friday, February 7, 2020, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

    I discuss three new methods for the quantum many-body problem. The first is the pinhole trace algorithm for first principles calculations of nuclear thermodynamics. I will present lattice Monte Carlo results for the liquid-vapor critical point. The second is the eigenvector continuation method for extrapolation and interpolation of quantum wave functions. I will show how it can be used as a fast emulator for quantum many-body calculations and as a resummation method for divergent perturbative expansions. The third is the projected cooling algorithm for quantum computers. This method is able to construct the localized ground state of any Hamiltonian with a translationally-invariant kinetic energy and interactions that vanish at infinity.

  97. RIKEN Lunch Seminar - CANCELLED

    "TBA"

    Presented by Yong Zhao, Brookhaven National Laboratory

    Thursday, January 30, 2020, 12 pm
    Building 510, Room 3-191

  98. NT/RIKEN Seminar

    "Towards precision event simulation for collider experiments"

    Presented by Stefan Hoeche, Fermilab

    Friday, January 24, 2020, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    Experimental analyses during the high-luminosity era of the LHC will call for an unprecedented level of precision in event simulation. With the computation of hard cross sections at next-to-leading order accuracy a solved problem, the focus of development has now shifted towards automated precision resummation, i.e. the extension of parton-showers to next-to-leading order accuracy and beyond the leading-color approximation. At the same time, seemingly mundane problems like the consistent matching of four- and five-flavor calculations at next-to-leading order accuracy need to be tackled in order to make precision forecasts for the measurement of b-jet associated processes such as ttbb. I will discuss the theoretical foundations and practical implications of new algorithms that solve these problems and briefly touch on the readiness of event generators for the next generation high-performance computers.

  99. RIKEN Lunch Seminar

    "NLO impact factor for inclusive photon+dijet production in e+A DIS at small x"

    Presented by Kaushik Roy, Stony Brook

    Thursday, January 23, 2020, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    We present the first computation of the NLO photon+dijet impact factor in e+A DIS at small x. When combined with the extant results for the JIMWLK small x evolution to NLLx accuracy, this result provides us with a prediction of the photon+dijet cross-section in e+A DIS to O( (\alpha_S)^3 ln(1/x) ) accuracy. The comparison of this result with photon+dijet measurements at a future EIC therefore provides a precision test of the systematics of gluon saturation. In the soft photon limit, one obtains a compact representation of the state-of-the art results for fully inclusive DIS. The novel techniques developed in this computation can also be applied to promote existing LO computations of photon+dijet production in p+A collisions to NLO+NLLx accuracy.

  100. NT/RIKEN Seminar

    "From Qubits to Quarks: Parton Physics on a Quantum Computer"

    Presented by Scott Lawrence

    Friday, December 20, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

    Quantum computers provide a unique way of computing real-time correlators from first principles, a task not yet achievable on classical computers due to the sign problem. The determination of the hadronic tensor on the Euclidean lattice is obstructed by the difficulty of converting Euclidean correlators to real-time correlators. This is a match made in heaven: a lattice field theory simulation on a quantum computer may provide access to PDFs. In this talk we discuss the way in which a quantum computer may naturally solve this problem, outline recent progress on simulating field theories on a quantum computer, and detail the resources needed to perform such a calculation.

  101. NT/RIKEN Seminar

    "Helicity-dependent generalization of the JIMWLK evolution and MV model"

    Presented by Florian Cougoulic

    Friday, December 13, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

    The small-x evolution equations for the quark and gluon helicity distribution have recently been constructed by finding sub-eikonal corrections to the eikonal shock wave formalism. Those equations are written for correlators of infinite light-cone Wilson lines along with the so-called polarized Wilson lines. Those equations close in the large N_c-limit (N_c is the number of quark colors), but also in the large N_c & N_f-limit (N_f is the number of quark flavors). However, in the shock wave formalism, no closed form can be obtained for arbitrary value of N_c and N_f. For the unpolarized case, the generalization of the Balitsky-Kovchegov equation is done by the Jalilian-Marian—Iancu—McLerran—Weigert—Leonidov—Kovner (JIMWLK) functional evolution equation. Such an approach for the small-x evolution of the helicity is beneficial for numerical evaluation at finite N_c and N_f (beyond previously used limit), and for the evaluation of helicity-dependent operator with an arbitrary number of Wilson lines. We derive an analogue of the JIMWLK evolution equation for the small-x evolution of helicity distributions and obtain an evolution equation for the target weight functional.

  102. NT/RIKEN Seminar

    "Probing Quark-Gluon Plasma at high resolution"

    Presented by Amit Kumar

    Friday, December 6, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

    In the study of the quark-gluon plasma (QGP) in high-energy heavy-ion collisions, jet quenching plays an essential role as hard probes of the properties of the dense strongly interacting matter. In this talk, we present an attempt to probe the underlying structure of the quark-gluon plasma (QGP) at high resolution, based on the extracted jet transport coefficient \hat{q}. We argue that the exchanged momentum k between the hard parton and the medium varies over a range of scales, and for k ≥ 1 GeV, \hat{q} can be expressed in terms of a parton distribution function (PDF). Calculations, based on this reconstructed \hat{q} are compared to data sensitive to the hardcore of jets i.e., the single hadron suppression in terms of the nuclear modification factor R_{AA} and the azimuthal anisotropy parameter v_{2}, as a function of transverse momentum p_{T}, centrality and energy of the collision. It is demonstrated that the scale evolution of the QGP-PDF is responsible for the reduction in the normalization of \hat{q} between fits to Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) data; a puzzle, first discovered by the JET collaboration.

  103. Special NT/RIKEN Seminar

    "Elementary correlation functions in QCD and their application"

    Presented by Nicolas Wink, Heidelberg

    Wednesday, December 4, 2019, 10 am
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

    The knowledge of all elementary correlation functions in a theory is sufficient to access all possible observables. The computation of these correlation functions in QCD within the Functional Renormalization Group is outlined. For applications, the shear and bulk viscosity in Yang-Mills, as well as diffusive transport for the critical mode in a Low-Energy Effective Theory of QCD are discussed.

  104. NT/RIKEN Seminar

    "Critical gravitational collapse and thermalization in small systems"

    Presented by Paul Chesler, Harvard University

    Friday, November 22, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Karthik

  105. CANCELLED - RIKEN Lunch Seminar

    "Shedding light on photon and dilepton spectral functions"

    Presented by Greg Jackson, University of Bern

    Thursday, November 21, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    Photons and dileptons offer themselves as 'clean' probes of the quark-gluon plasma because they are unlikely to reinteract once produced. Their emission rates are given via the vector channel spectral function, an object that can ultimately be reconstructed by analytic continuation of lattice data. To confront perturbative results with that data, the NLO corrections are needed in all domains that affect the associated imaginary-time correlator, namely for energies above, below and in the vicinity of the light cone. We summarize recent progress here and, to control an unavoidable snag, we also determine these corrections for the transverse and longitudinal polarizations separately. Our results should help to scrutinize direct spectral reconstruction attempts from lattice QCD.

  106. RIKEN Lunch Seminar

    "Revisiting the discovery potential of the isobar run at RHIC"

    Presented by Alba Soto Ontoso, BNL

    Thursday, November 14, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    During the spring of 2018, the Relativistic Heavy-Ion Collider carried out an isobar run consisting of Ru+Ru and Zr+Zr collisions at 200 GeV. The main objective of such experimental program was the unambiguous observation of a Chiral Magnetic Effect-driven charge separation. In this talk, I will demonstrate how an experimentally confirmed property of the nuclear structure of Zr, i.e. its neutron skin, significantly reduces the feasibility of such a finding. This study provides a much needed theoretical baseline to meaningfully interpret the recorded experimental data by combining state-of-the art nuclear structure techniques with a dynamical description of heavy-ion collisions in terms of a novel transport model, SMASH.

  107. Special NT/RIKEN Seminar

    "Relaxation Time for Strange Quark Spin in Rotating Quark-Gluon Plasma"

    Presented by Joseph Kapusta

    Thursday, October 31, 2019, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Nikhil Karthik

  108. NT/RIKEN Seminar

    "Detectability of phase transitions from multi-messenger observations"

    Presented by Sophia Han, Ohio University

    Friday, October 25, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Nikhil Karthik

    There is as yet no firm evidence for quark matter in neutron stars. This is mainly because of the lack of direct probes of the opaque neutron star interior, and the lack of clear qualitative difference between hadronic and quark phases. The detection of GW170817 has offered a first example of how gravitational waves can be used to constrain the equation of state (EoS) of ultra-dense matter. We shall discuss taking into account currently available information how to reveal possible phase transitions in neutron stars: the steadily growing body of astrophysical data and supported laboratory experiments should eventually allow us to narrow down the options by combining these various observations. We survey the proposed signatures of exotic matter, and emphasize the importance of data from neutron star mergers.

  109. NT/RIKEN Seminar

    "The bulk viscosity of QCD in the chiral limit"

    Presented by Derek Teaney, Stony Brook

    Friday, October 18, 2019, 2 pm
    Building 510, CFNS Room 2-38

    In the chiral limit, the long distance effective theory of QCD at finite temperature is not hydrodynamics but a kind of non-abelian superfluid hydrodynamics. We describe this theory and its viscous corrections, including also a correction due to the finite quark mass. At finite quark mass, the long distance theory is ordinary hydrodynamics, and the superfluid theory then just determines non-analytic in the quark mass corrections to the transport coefficients of QCD, akin to the "long time tails" of hydro. We show how this works out for the bulk viscosity. In chiral perturbation theory the dissipative parameters of the superfluid theory can be computed diagrammatically, and we do this. These results then determine the leading order the bulk viscosity of the pion gas close to the chiral limit.

  110. RIKEN Lunch Seminar

    "Bottomonia in QGP from lattice QCD: Beyond the ground states"

    Presented by Rasmus Larsen, BNL

    Thursday, October 17, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    Using novel lattice (non-relativistic) QCD techniques, for the first time, we will present results pertaining to the fate of Υ(1S), Υ(2S) and Υ(3S) in QGP. We will present results on how the masses of these states change with temperature, as well as how their spatial sizes change. Finally, we will also show new lattice QCD results on excited P-wave bottomonia in QGP.

  111. NT/RIKEN Seminar

    "JIMWLK equation from quantum-classical correspondence"

    Presented by Ming Li, University of Connecticut

    Friday, October 11, 2019, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Niklas Mueller

    In this talk, I will examine the status of the JIMWLK evolution equation in relation to the effective density matrix of a high energy hadronic system. The high energy evolution of this density matrix which is associated with the Hilbert space completely spanned by color charge density operators has the form of Lindblad equation. The JIMWLK equation is reproduced by mapping this Lindblad type quantum mechanical equation onto the classical phase space of the system using Weyl's correspondence rules.

  112. NT/RIKEN Seminar

    "Resurgence and Non-Perturbative Physics"

    Presented by Gerald Dunne, University of Connecticut

    Friday, October 4, 2019, 1 pm
    Building 510, CFNS Room 2-38

    Hosted by: Niklas Mueller

    I will review the basic ideas behind the connections between resurgent asymptotics and physics, and report on current applications to quantum field theory and phase transitions.

  113. RIKEN Lunch Seminar

    "Chiral charge dynamics in Abelian gauge theories at finite temperature"

    Presented by Adrien Florio, École polytechnique fédérale de Lausanne

    Thursday, October 3, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    The chiral anomaly present in the standard model can have important phenomenological consequences, especially in cosmology and heavy-ions physics. In this talk, I will focus on the contribution from the Abelian gauge fields. Despite an absence of topologically distinct sectors, they have a surprisingly rich vacuum dynamics, partly because of the chiral anomaly. I will present results obtained from real-time classical lattice simulations of a U(1) gauge field in the presence of a chiral chemical potential. They account for short distance fluctuations, contrary to effective descriptions such as Magneto-Hydrodynamics (MHD). I will discuss various phenomena, like inverse magnetic cascade, which occur in this system. In particular, in presence of a background magnetic field, the chemical potential exponentially decays. The associated chiral decay rate is related to the diffusion of the Abelian Chern-Simons number in a magnetic background, in the absence of chemical potential. The rate obtained from the simulations is an order of magnitude larger than the one predicted by MHD. If this result is shown to be robust under corrections such as Hard Thermal Loops, it will call for a revision of the implications of fermion number and chiral number non-conservation in Abelian theory at finite temperature.

  114. NT/RIKEN Seminar

    "Observing the deformation of nuclei with relativistic nuclear collisions"

    Presented by Giuliano Giacalone, IPhT - Saclay

    Friday, September 27, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    The geometry of overlap between two nuclei interacting at high energy determines many of the observables typically investigated in heavy-ion-collision analyses, such as average transverse momenta () and azimuthal anisotropies of the emitted particle distributions. If the colliding nuclei are non-spherical, e.g., if they present a quadrupole deformation and look like ellipsoids, the geometry of interaction experiences nontrivial fluctuations due to the random orientation of the colliding bodies. I introduce an 'event-shape engineering' procedure that allows one to probe the quadrupole deformation of the colliding ions. The method is straightforward. One selects a batch of high-multiplicity (ultracentral) collisions, and within this batch looks at events that present an abnormally large or small of the produced hadrons. I show that these events correspond to configurations in which the colliding nuclei are overlapping along the longer (shorter) side of the prolate (oblate) ellipsoids. In these events, the interaction region has an elliptical shape, whose eccentricity is closely related to the quadrupole deformation of the considered nuclei. Therefore, for collisions of nuclei that are significantly deformed (e.g. 238U and 129Xe nuclei collided at RHIC and LHC) I predict a strong enhancement of elliptic flow in the tails of the distributions of ultracentral events. If validated by experimental data, this method would provide a robust tool to observe the deformations of nuclear ground states at particle colliders (in particular at RHIC).

  115. RIKEN Lunch Seminar

    "Rapidity correlators at unequal rapidity"

    Presented by Andrecia Ramnath, University of Jyvaskyla

    Thursday, September 26, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    Unequal rapidity correlations can be studied within the stochastic Langevin picture of JIMWLK evolution in the Colour Glass Condensate effective field theory. By evolving the classical field in the direct and complex conjugate amplitudes, the Langevin formalism can be used to study two-particle production at large rapidity separations. We show how the evolution between the rapidities of the two produced particles can be expressed as a linear equation, even in the full nonlinear limit. In addition, we show how the Langevin formalism for two-particle correlations reduces to a BFKL picture in the dilute limit and in momentum space, providing an interpretation of BFKL evolution as a stochastic process for colour charges.

  116. NT/RIKEN Seminar - CANCELLED

    "The bulk viscosity of QCD in the chiral limit"

    Presented by Derek Teaney, Stony Brook

    Friday, September 20, 2019, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Niklas Mueller

    In the chiral limit, the long distance effective theory of QCD at finite temperature is not hydrodynamics but a kind of non-abelian superfluid hydrodynamics. We describe this theory and its viscous corrections, including also a correction due to the finite quark mass. At finite quark mass, the long distance theory is ordinary hydrodynamics, and the superfluid theory then just determines non-analytic in the quark mass corrections to the transport coefficients of QCD, akin to the "long time tails" of hydro. We show how this works out for the bulk viscosity. In chiral perturbation theory the dissipative parameters of the superfluid theory can be computed diagrammatically, and we do this. These results then determine the leading order the bulk viscosity of the pion gas close to the chiral limit.

  117. NT/RIKEN Seminar

    "The bulk viscosity of QCD in the chiral limit"

    Presented by Derek Teaney, Stony Brook

    Thursday, September 19, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    In the chiral limit, the long distance effective theory of QCD at finite temperature is not hydrodynamics but a kind of non-abelian superfluid hydrodynamics. We describe this theory and its viscous corrections, including also a correction due to the finite quark mass. At finite quark mass, the long distance theory is ordinary hydrodynamics, and the superfluid theory then just determines non-analytic in the quark mass corrections to the transport coefficients of QCD, akin to the "long time tails" of hydro. We show how this works out for the bulk viscosity. In chiral perturbation theory the dissipative parameters of the superfluid theory can be computed diagrammatically, and we do this. These results then determine the leading order the bulk viscosity of the pion gas close to the chiral limit.

  118. RIKEN Lunch Seminar

    "Deeply inelastic scattering structure functions on a hybrid quantum computer"

    Presented by Andrey Tarasov, BNL

    Thursday, September 12, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    Computation of DIS structure functions from first principles is an outstanding problem in Quantum Chromodynamics (QCD) as it involves matrix elements of products of electromagnetic currents that are light-like separated in Minkowski spacetime. Since Monte Carlo computations in lattice QCD are only robust in Euclidean spacetime, it is worthwhile to ask whether simulations on a quantum computer can be beneficial. In my talk I will outline a strategy to compute deeply inelastic scattering structure functions on a hybrid quantum computer which is based on representation of the fermion determinant in the QCD effective action as a quantum mechanical "worldline" path integral over fermionic and bosonic degrees of freedom. The proper time evolution of these worldlines can be determined on a quantum computer. While extremely challenging in general, the problem simplifies in the Regge limit of QCD, where the interaction of the worldlines with gauge fields is strongly localized in proper time and the corresponding quantum circuits can be written down. As a first application, we employ the Color Glass Condensate effective theory to construct the quantum algorithm for a simple dipole model of the F2 structure function. We outline further how this computation scales up in complexity and extends in scope to other real-time correlation functions.

  119. NT/RIKEN Seminar

    "Qubit Regularization of Quantum Field Theories"

    Presented by Shailesh Chandrasekharan, Duke University

    Friday, September 6, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    Motivated by the desire to study quantum field theories on a quantum computer, we propose a new type of regularization of quantum field theories where in addition to the usual lattice regularization, quantum field theories are constructed with a finite dimensional Hilbert space per lattice site. This is particularly relevant for studying bosonic field theories using a quantum computer since traditional lattice regularization assumes an infinite dimensional Hilbert space per lattice site and hence difficult to formulate on a quantum computer. Here we show that a two qubit model is sufficient to recover the 3d Wilson-Fisher fixed point and the 4d Gaussian fixed point of the O(3) sigma model. On the other hand in 2d, our qubit model does not seem to have a continuum limit although we have to study large lattices to establish this fact. We discuss modifications of our model that could perhaps yield a continuum limit.

  120. RIKEN Lunch Seminar

    "Quantum Black Hole Entropy from 4d Supersymmetric Cardy formula"

    Presented by Masazumi Honda, Cambridge

    Thursday, August 29, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    I will talk about supersymmetric index of 4d N=1 supersymmetric theories on S^1xM_3 which counts supersymmetric states. In the first part, I will discuss a general formula to describe an asymptotic behaviour of the index in the limit of shrinking S^1 which we refer to as 4d (refined) supersymmetric Cardy formula. This part is based on arXiv:1611.00380 with Lorenzo Di Pietro. In the second part, I will apply this formula to black hole physics. I will mainly focus on superconformal index of SU(N) N=4 super Yang-Mills theory which is expected to be dual to type IIB superstring theory on AdS_5 x S^5. We will see that the index in the large-N limit reproduces the Bekenstein-Hawking entropy of rotating charged BPS black hole on the gravity side. Our result for finite N makes a prediction to the black hole entropy with full quantum corrections. The second part is based on arXiv:1901.08091.

  121. NT/RIKEN Seminar

    "Symmetries in quantum field theory and quantum gravity"

    Presented by Daniel Harlow, MIT

    Friday, August 23, 2019, 1:15 pm
    Building 510, CFNS Seminar room 2-38

    Hosted by: Niklas Mueller

    It has long been suspected that symmetries in quantum gravity are highly constrained. In this talk I will describe joint work with Hirosi Ooguri, where we use the power of the AdS/CFT correspondence to prove three conjectures of this type: that there are no global symmetries, that there must be objects transforming in all representations of any gauge symmetry, and that any gauge group must be compact. Real world implications include the existence of magnetic monopoles and neutrinoless double beta decay, although we so far are unable to give estimates for when these should be seen. An important point, which we dwell on at length, is the proper definition of gauge and global symmetries in quantum field theory.

  122. NT/RIKEN

    "Effective and temperature-dependent viscosities in a hydrodynamically-expanding QCD plasma"

    Presented by Jean-Francois Paquet, Duke University

    Friday, August 16, 2019, 2 pm
    Building 510, CFNS room 2-38

    Hosted by: Niklas Mueller

    The shear and bulk viscosities of QCD are understood to have non-trivial temperature dependence. The quark-gluon plasma created at RHIC and the LHC provides a unique probe of this temperature dependence for temperatures ranging from ∼150 ~MeV to ∼400−600 MeV. Values of viscosities commonly quoted for the quark-gluon plasma, e.g. η/s∼0.1−0.2 for the shear viscosity to entropy density ratio, are understood to represent ``effective viscosities'', which combine the actual temperature-dependence of the transport coefficient with the complex temperature profile of the quark-gluon plasma. Using 0+1D Bjorken hydrodynamics as starting point, we provide a precise definition of effective viscosity for first-order (Navier-Stokes) hydrodynamics. We examine the role of the equation of state by comparing a QCD fluid with a conformal one. We use this definition of effective viscosity to obtain families of bulk viscosities ζ/s(T) that have different temperature dependence but nevertheless produce matching temperature evolutions in 0+1D hydrodynamics. We further extend the definition of effective viscosity to second-order (Israel-Stewart) Bjorken hydrodynamics. We express the second-order effective viscosity in terms of the initial bulk pressure of the system and its first-order effective viscosity, and quantify the approximate degeneracy of these latter two quantities in Bjorken hydrodynamics. We discuss extensions of this work beyond 0+1D, and review implications for phenomenological studies of heavy ion collisions.

  123. RIKEN Lunch Seminar

    "Mean field approach to the Fisher information matrix in deep neural networks"

    Presented by Ryo Karakida, AIST, National Institute of Advanced Industrial Science and Technology

    Thursday, August 15, 2019, 12 pm
    Building 510, Room 1-224

    Hosted by: Akio Tomiya

  124. Nuclear Theory / RIKEN Seminar

    "DIS on a Quantum Extremal RN-AdS Black Hole: with Application to DIS on a Nucleus"

    Presented by Kiminad Mamo, Stony Brook University

    Thursday, August 8, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    We consider deep inelastic scattering (DIS) on a dense nucleus described as an extremal RN-AdS black hole with holographic quantum fermions in the bulk. We find that the R-ratio (the ratio of the structure function of the black hole to proton) exhibit shadowing for x < 0.1, anti-shadowing for 0.1 < x < 0.3, EMC-like effect for 0.3 < x < 0.8 and Fermi motion for x > 0.8 in a qualitative agreement with the experimental observation of the ratio for DIS on nucleus for all range of x. We also take the dilute limit of the black hole and show that its R-ratio exhibits EMC-like effect for 0.2 < x < 0.8 and the Fermi motion for x > 0.8, and no shadowing is observed in the dilute limit.

  125. NT/RIKEN Seminar

    "Perturbation Theory of Non-Perturbative QCD"

    Presented by Fabio Siringo, University of Catania

    Friday, August 2, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    A purely analytical approach to non-perturbative QCD is discussed. The exact, gauge-fixed, Faddeev-Popov Lagrangian of Yang-Mills theory is studied by the screened massive expansion which emerges from a mere change of the expansion point of ordinary perturbation theory. The gluon propagator has gauge-invariant complex conjugated poles which might give a direct dynamical proof of gluon confinement. Their genuine nature is discussed. Because of BRST symmetry, the analytic properties and the poles are shown to play a central role in the optimization of the expansion, which becomes a very predictive and ab initio tool. While in excellent agreement with the lattice data in the Euclidean space, the expansion provides valuable information in sectors which are not easily explored on the lattice, like Minkowski space and a generic covariant gauge. Moreover, even in the Euclidean space, the method gives a lattice-independent estimate of the running coupling in the continuum limit.

  126. RIKEN Lunch Seminar

    "Deciphering the z_g distribution in ultrarelativistic heavy ion collisions"

    Presented by Paul Caucal, Saclay

    Thursday, July 25, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

  127. NT/RIKEN Seminar

    "Topological Superconducting Qubits"

    Presented by Javad Shabani, Center for Quantum Phenomena NYU

    Friday, July 12, 2019, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Niklas Mueller

    Topological superconductivity hosts exotic quasi-particle excitations including Majorana bound states which hold promise for fault-tolerant quantum computing. The theory predicts emergence of Majorana bound states is accompanied by a topological phase transition. We show experimentally in epitaxial Al/InAs Josephson junctions a transition between trivial and topological superconductivity. We observe a minimum of the critical current at the topological transition, indicating a closing and reopening of the superconducting gap induced in InAs, with increasing magnetic field. By embedding the Josephson junction in a phase-sensitive loop geometry, we measure a π-jump in the superconducting phase across the junction when the system is driven through the topological transition. We present a scalable topological qubit architecture to study coherence for computing applications. Funded by DARPA TEE program.

  128. NT/RIKEN Seminar

    "D meson mixing via dispersion relation"

    Presented by Hsiang-nan Li, National Center for Theoretical Sciences, Physics Division, Taiwan

    Friday, June 14, 2019, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Niklas Mueller

    In this talk I will explain how to calculate the D meson mixing parameters x and y in the Standard Model. Charm physics is notoriously difficult, because most effective theories and perturbation theories do not apply well. I propose to study the D meson mixing via a dispersion relation, which relates low mass dynamics to high mass one. Taking heavy quark results as inputs in the high mass region, we obtain x and y consistent with experimental data at least in order of magnitude.

  129. RIKEN Lunch Seminar

    "Applications of machine learning to computational physics"

    Presented by Dr Akio Tomiya, RBRC

    Thursday, May 30, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    In this talk, I would like to talk about my works with machine learning. I plan to introduce my works which related to lattice QCD research: detection of phase transition in classical spin systems [arXiv 1609.09087, 1812.01522], configuration generation [1712.03893 + some]

  130. NT/RIKEN Seminar

    "Pieces of the Puzzle: Reaching QCD on Quantum Computers"

    Presented by Henry Lamm, UMD

    Friday, May 24, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    The advent of quantum computing for scientific research presents the possibility of calculating time-dependent observables like viscosity and parton distributions from QCD. In order to utilize this new tool, a number of theoretical and practical issues must be addressed related to efficiently digitize, initialize, propagate, and evaluate quantum field theory. In this talk, I will discuss a number of projects being undertaken by the NuQS collaboration to realize calculations on NISQ era and beyond quantum computers.

  131. RIKEN Lunch Seminar

    "Complex saddle points of path integrals"

    Presented by Semeon Valgushev, BNL

    Thursday, May 23, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    In this talk, we discuss the physical role of complex saddle points of path integrals. In the first case study, we analyze saddle point structure of two-dimensional lattice gauge theory represented as Gross-Witten-Wadia unitary matrix model. We find that non-perturbative physics in the strong coupling phase can be understood in terms of new family of complex saddle points those properties are connected to resurgent structure of the 1/N expansion. In the second case study, we discuss the sign problem in fermionic systems at finite density and the possibility to alleviate it with the help of defomations of integration contour into complex space on the example of two-dimensional Hubbard model.

  132. NT/RIKEN Seminar

    "The non-equilibrium attractor: Beyond hydrodynamics"

    Presented by Michael Strickland, Kent State University

    Friday, May 10, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

  133. RIKEN Lunch Seminar

    "Electric dipole moments in the era of the LHC"

    Presented by Jordy de Vries, University of Massachusetts Amherst, Riken BNL

    Thursday, May 9, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    The search for an understanding of fundamental particle physics that goes beyond the Standard Model (SM) has grown into a worldwide titanic effort. Low-energy precision experiments are complementary to collider searches and, in certain cases, can even probe higher energy scales directly. However, the interpretation of a potential signal, or lack thereof, is complicated because of the non-perturbative nature of low-energy QCD. I will use the search for electric dipole moments (EDMs), which aims to discover beyond-the-SM CP violation, as an example to illustrate these difficulties and how they can be overcome by combining (chiral) effective field theory and lattice QCD. I discuss how EDM experiments involving complex systems like nucleons, nuclei, atoms, and molecules constrain possible CP-violating interactions involving the Higgs boson, how these constraints match up to direct LHC searches, and the relevance of and strategies for the improvement of the hadronic and nuclear theory.

  134. NT/RIKEN Seminar

    "Relativistic Hydrodynamic Fluctuations"

    Presented by Gokce Basar, UiC

    Friday, May 3, 2019, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Niklas Mueller

    We present a general systematic formalism for describing dynamics of fluctuations in an arbitrary relativistic hydrodynamic flow, including their feedback (known as long-time hydrodynamic tails) in a deterministic way. The fluctuations are described by two-point equal-time correlation functions. We introduce a definition of equal time in a situation where the local rest frame is determined by the local flow velocity, and a method of taking derivatives and Wigner transforms of such equal-time correlation functions, which we call confluent. The Wigner functions satisfy evolution equations that describes the relaxation of the out-of-equilibrium modes. We find that the equations for confluent Wigner functions nontrivially match with the kinetic equation for phonons propagating on an arbitrary background, including relativistic inertial and Coriolis forces due to acceleration and vorticity of the flow. We also describe the procedure of renormalization of short-distance singularities which eliminates cutoff dependence, allowing efficient numerical implementation of these equations.

  135. RIKEN Lunch Seminar

    "The Chiral Qubit: quantum computing with chiral anomaly"

    Presented by Dmitri Kharzeev, Stony Brook University and BNL

    Thursday, May 2, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    The quantum chiral anomaly enables a nearly dissipationless current in the presence of chirality imbalance and magnetic field – this is the Chiral Magnetic Effect (CME), observed recently in Dirac and Weyl semimetals. We propose to utilize the CME for the design of qubits potentially capable of operating at THz frequency, room temperature, and the coherence time to gate time ratio of about 10^4 . The proposed "Chiral Qubit" is a micron-scale ring made of a Weyl or Dirac semimetal, with the |0> and |1> quantum states corresponding to the symmetric and antisymmetric superpositions of quantum states describing chiral fermions circulating along the ring clockwise and counter-clockwise. A fractional magnetic flux through the ring induces a quantum superposition of the |0> and |1> quantum states. The entanglement of qubits can be implemented through the near-field THz frequency electromagnetic fields.

  136. RIKEN Lunch Seminar

    "Partons from the Path-Integral Formalism of the Hadronic Tensor"

    Presented by Keh-Fei Liu, University of Kentucky

    Thursday, April 25, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

  137. NT/RIKEN Seminar

    "Parton distributions in Euclidean space"

    Presented by Anatoly Radyushkin, ODU/JLab

    Friday, April 19, 2019, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Niklas Mueller

    To extract parton distributions from the lattice simulations, one needs to consider matrix elements M(z,p) of bilocal correlators of parton fields [generically written as φ(0)φ(z)] at spacelike separations z=(0,0,0,z_3). A transition to PDFs may be proceeded by taking a Fourier transform either with respect to z_3 for fixed p_3 (which gives X. Ji's quasi-PDFs), or with respect to the Lorentz-invariant variable ν=-(zp) for fixed values of another Lorentz invariant z^2 [which results in pseudo-PDFs].These functions are interesting on their own, and I will discuss, in the continuum case, their general properties, the connection between the two types of functions, and their relation with the usual light-cone PDFs. I will outline the algorithm of extracting the PDFs through the use of the so-called "reduced Ioffe-time distributions",and illustrate this pseudo-PDF-oriented approach on the example of exploratory lattice simulations performed by Orginos et al.

  138. NT / RIKEN Seminar

    "A Complex Path Around the Sign Problem"

    Presented by Paolo Bedaque, U Maryland

    Friday, April 12, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    The famous "sign problem" is the main roadblock in the path to a Monte Carlo solution of QCD at finite densities and the study of real time dynamics. We review a recent developed approach to this problem based on deforming the domain of integration of the oath integral into complex field space. After discussing the math involved in the complex analysis of multidimensional spaces we will talk about the advantages/disadvantages of using Lefschetz thimbles, "learnifolds" and "optimized manifolds" as the alternative integration manifold as well as the algorithms that go with them. Several examples of lower dimensional field theories will be presented.

  139. NT / RIKEN seminar

    "The Color Glass Condensate density matrix: Lindblad evolution, entanglement entropy and Wigner functional"

    Presented by Alex Kovner, U Connecticut

    Friday, April 5, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    We introduce the notion of the Color Glass Condensate (CGC) density matrix ρ̂ . This generalizes the concept of probability density for the distribution of the color charges in the hadronic wave function and is consistent with understanding the CGC as an effective theory after integration of part of the hadronic degrees of freedom. We derive the evolution equations for the density matrix and show that it has the celebrated Kossakowsky-Lindblad form describing the non-unitary evolution of the density matrix of an open system. Additionally, we consider the dilute limit and demonstrate that, at large rapidity, the entanglement entropy of the density matrix grows linearly with rapidity according to dSe/dy=γ, where γ is the leading BFKL eigenvalue. We also discuss the evolution of ρ̂ in the saturated regime and relate it to the Levin-Tuchin law and find that the entropy again grows linearly with rapidity, but at a slower rate. Finally we introduce the Wigner functional derived from this density matrix and discuss how it can be used to determine the distribution of color currents, which may be instrumental in understanding dynamical features of QCD at high energy.

  140. NT/RIKEN Seminar

    "Toward a unified description of both low and high ptparticle production in high energy collisions"

    Presented by Jamal Jalilian-Marian, Baruch College, City University of New York

    Friday, March 29, 2019, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    Inclusive particle production at high p_t is successfully described by perturbative QCD using collinear factorization formalism with DGLAP evolution of the parton distribution functions. This formalism breaks down at small Bjorken x (high energy) due to high gluon density (gluon saturation) effects. The Color Glass Condensate (CGC) formalism is an effective action approach to particle production at small Bjorken x (low p_t) which includes gluon saturation. The CGC formalism nevertheless breaks down at intermediate/large Bjorken x, corresponding to the high p_t kinematic region in high energy collisions. Here we describe the first steps taken towards the derivation of a new formalism, with the ultimate goal of having a unified formalism for particle production at both low and high p_t in high energy hadronic/heavy ion collisions.

  141. High Energy / Nuclear Theory / RIKEN Seminars

    "Lattice Workshop for US -Japan Intensity Frontier Incubation (1/1)"

    Wednesday, March 27, 2019, 9 am
    TBD

    Hosted by: Sally Dawson

  142. High Energy / Nuclear Theory / RIKEN Seminars

    "Lattice Workshop for US -Japan Intensity Frontier Incubation (1/1)"

    Tuesday, March 26, 2019, 9 am
    TBD

    Hosted by: Sally Dawson

  143. High Energy / Nuclear Theory / RIKEN Seminars

    "Lattice Workshop for US -Japan Intensity Frontier Incubation (1/1)"

    Monday, March 25, 2019, 9 am
    TBD

    Hosted by: Sally Dawson

  144. CANCELED - NT/RIKEN Seminar

    "TBA"

    Presented by Alex Kovner, University of Connecticut

    Friday, March 22, 2019, 2 pm
    Building 510, Room 2-38

    Hosted by: Niklas Mueller

  145. NT/RIKEN Seminar

    "Baryons as Quantum Hall Droplets"

    Presented by Zohar Komargodski, Simons Center, Stony Brook

    Friday, March 15, 2019, 2 pm
    Building 510, CFNS Room 2-38

    Hosted by: Niklas Mueller

    We revisit the problem of baryons in the large N limit of Quantum Chromodynamics. A special case in which the theory of Skyrmions is inapplicable is one-flavor QCD, where there are no light pions to construct the baryon from. More generally, the description of baryons made out of predominantly one flavor within the Skyrmion model is unsatisfactory. We propose a model for such baryons, where the baryons are interpreted as quantum Hall droplets. An important element in our construction is an extended, 2+1 dimensional, meta-stable configuration of the η′ particle. Baryon number is identified with a magnetic symmetry on the 2+1 dimensional sheet. If the sheet has a boundary, there are finite energy chiral excitations which carry baryon number. These chiral excitations are analogous to the electron in the fractional quantum Hall effect. Studying the chiral vertex operators we are able to determine the spin, isospin, and certain excitations of the droplet. In addition, balancing the tension of the droplet against the energy stored at the boundary we estimate the size and mass of the baryons. The mass, size, spin, isospin, and excitations that we find agree with phenomenological expectations.

  146. Joint NT/RIKEN/CFNS Seminar

    "Measuring color memory in a color glass condensate"

    Presented by Ana-Maria Raclariu, Harvard University

    Thursday, February 28, 2019, 4 pm
    Building 510, Room 2-38 CFNS Seminar Room

    Hosted by: Niklas Mueller

  147. NT / RIKEN Seminar

    "Quantum Chaos, Wormholes and the Sachdev-Ye-Kitaev Model"

    Presented by Jacobus Verbaarschot, Stony Brook University

    Friday, February 22, 2019, 2 pm
    2-38 CFNS Seminar Room

    Hosted by: Niklas Mueller

    The Sachdev-Ye-Kitaev (SYK) model has a long history in nuclear physics where its precursor was introduced as a model for the two-body nuclear interaction to describe the spectra of complex nuclei. Most notably, its level density is given by the Bethe formula and its level correlations are consistent with chaotic motion of the nucleons. Recently, this model received a great of attention as a solvable model for the quantum states of a black hole, exactly because of these properties. In this lecture we introduce the SYK model from a nuclear physics perspective and discuss its chaotic nature and its relation with black hole physics. We end with a summary of recent work on two SYK models coupled by a spin-spin interaction as a model for wormholes.

  148. RIKEN Lunch Seminar

    "Chiral Photocurrents and Terahertz Emission in Dirac and Weyl Materials"

    Presented by Mr. Sahal Kaushik, Stony Brook University

    Thursday, February 14, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    Recently, chiral photocurrents have been observed in Weyl materials. We propose a new mechanism for photocurrents in Dirac materials in the presence of magnetic fields, that does not depend on any asymmetries of the crystal. This Chiral Magnetic Photocurrent would be an independent probe of the chiral anomaly. We also also discuss an observation of terahertz emission in the Weyl material TaAs with tunable ellipticity, due to chiral photocurrents induced by an ultrafast near infrared laser.

  149. NT / RIKEN Seminar

    "Realizing relativistic dynamics with slow light polaritons at room temperature"

    Presented by Eden Figueroa, Stony Brook University

    Friday, February 8, 2019, 2 pm
    CFNS Seminar Room

    Hosted by: Niklas Mueller

    Experimental verification of relativistic field theory models requires accelerator experiments. A possible pathway that could help understanding the dynamics of such models for bosons or fermions is the use of quantum technology in the form of quantum analog simulators. In this talk we will explore the possibility of generating nonlinear Dirac-type Hamiltonians using coherent superpositions of photons and spin wave excitations of atoms. Our realization uses a driven slow-light setup, where photons mimic the Dirac fields and different dynamics can be implemented and tuned by adjusting optical parameters. We will show our progress tin building a quantum simulator of the Jackiw-Rebbi model using highly-interacting photons strongly coupled to a room temperature atomic ensemble. We have identified suitable conditions in which the input photons dispersion relations can be tuned to a spinor of light configuration, mimicking the Dirac regime and providing a framework to create tunable interactions and varying mass terms. Lastly, we will show our vision to scale these ideas to multiple interacting fermions.

  150. RIKEN Lunch Seminar

    "Modification of the nucleon-nucleon potential and nuclear correlations due to the QCD critical point"

    Presented by Juan M. Torres-Rincon, Stony Brook University

    Thursday, February 7, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    The scalar-isoscalar mode of QCD becomes lighter/nearly massless close to the chiral transition/second-order critical point. This mode is the main responsible for the attractive part of the nucleon-nucleon potential at distances of 1-2 fm. Therefore, a long-range strong attraction among nucleons is predicted to develop close to the QCD critical point. Using the Walecka-Serot model for the NN potential we study the effects of the critical mode in a system of nucleons and mesons using a Molecular Dynamics+Langevin equations for the freeze-out conditions of heavy-ion collisions. Beyond mean field, we observe strong nucleon correlations leading to baryon clustering. We propose that light-nuclei formation, together with an enhancement of cumulants of the proton distribution can signal the presence of the QCD critical point.

  151. RIKEN Lunch Seminar

    "Sorting out jet quenching in heavy-ion collisions"

    Presented by Jasmine Brewer, Massachusetts Institute of Technology

    Thursday, January 31, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    We introduce a new "quantile'' analysis strategy to study the modification of jets as they traverse through a droplet of quark-gluon plasma. To date, most jet modification studies have been based on comparing the jet properties measured in heavy-ion collisions to a proton-proton baseline at the same reconstructed jet transverse momentum pT. It is well known, however, that the quenching of jets from their interaction with the medium leads to a migration of jets from higher to lower pT, making it challenging to directly infer the degree and mechanism of jet energy loss. Our proposed quantile matching procedure is inspired by (but not reliant on) the approximate monotonicity of energy loss in the jet pT. In this strategy, jets in heavy-ion collisions ordered by pT are viewed as modified versions of the same number of highest-energy jets in proton-proton collisions. Despite non-monotonic fluctuations in the energy loss, we use an event generator to validate the strong correlation between the pT of the parton that initiates a heavy-ion jet and the pT of the vacuum jet which corresponds to it via the quantile procedure. We demonstrate that this strategy both provides a complementary way to study jet modification and mitigates the effect of pT migration in heavy-ion collisions.

  152. Nuclear Theory / RIKEN Seminar

    "Effective field theory of hydrodynamics"

    Presented by Paolo Glorioso, Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago

    Friday, January 25, 2019, 2 pm
    CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    I will give an overview of our work on developing an effective field theory of dissipative hydrodynamics. The formulation is based on the Schwinger-Keldysh formalism, which provides a functional approach that naturally includes dissipation and fluctuations. Hydrodynamics is implemented by introducing suitable degrees of freedom and symmetries. I will then discuss two important by-products. First, the second law of thermodynamics, which in the traditional approach is imposed at phenomenological level, is here obtained from a basic symmetry principle together with constraints from unitarity. Second, I will show consistency with unitarity and causality of the hydrodynamic path-integral at all loops, which leads to the first systematic framework to compute hydrodynamic fluctuations.

  153. RIKEN Lunch Seminar

    "Quarkonium production in heavy ion collisions: open quantum system, effective field theory and transport equations"

    Presented by Xiaojun Yao, Duke University

    Thursday, January 24, 2019, 12 pm
    Building 510, Room 1-224

    Hosted by: Yuta Kikuchi

    In this talk, I will present a connection between two approaches of studying quarkonium dynamics inside quark-gluon plasma: the open quantum system formalism and the transport equation. I will discuss insights from the perspective of quantum information. I will show that under the weak coupling and Markovian approximations, the Lindblad equation turns to a Boltzmann transport equation after a Wigner transform is applied to the system density matrix. I will demonstrate how the separation of physical scales justifies the approximations, by using effective field theory of QCD. Finally, I will show some phenomenological results based on the derived transport equation.

  154. Nuclear Theory / RIKEN Seminar

    "Chiral Vortical Effect For An Arbitrary Spin"

    Presented by Andrey Sadofyev, Los Alamos National Lab

    Friday, January 18, 2019, 2 pm
    CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    Chiral effects attracted significant attention in the literature. Recently, a generalization of chiral vortical effect (CVE) to systems of photons was suggested. In this talk I will discuss the relation of this new transport to the topological phase of photons and show that, in general, CVE can take place in rotating systems of massless particles with any spin.

  155. RIKEN Lunch Seminar

    "Proton decay matrix elements on lattice"

    Presented by Mr. Jun-sik Yoo, Stony Brook University

    Thursday, January 17, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    Proton decay is one of possible signatures of baryon number violation, which has to exist to explain the baryon asymmetry and the existence of nuclear matter. Proton decay is one of natural implications of the Grand Unification Theory. After integrating out the high energy degrees of freedom, the baryon number violation operator that mediates proton decay can be found as the composite operator of standard model fields. We discuss the hadronic matrix elements of this BV operator made of three quarks and a lepton. We will start from the current experimental bound of proton lifetime. We present preliminary results of matrix element calculation done with the 2+1 dynamical flavor domain wall fermions at the physical point. We will discuss the proton decay channels that no matrix element has been calculated on the lattice.

  156. RIKEN Lunch Seminar

    "A novel background subtraction method for jet studies in heavy ion collisions"

    Presented by Alba Soto Ontoso, BNL

    Thursday, January 10, 2019, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

  157. NT/RIKEN Seminar

    "Lattice QCD Input for Fundamental Symmetry Tests"

    Presented by Micheal Wagman, MIT

    Friday, December 14, 2018, 2 pm
    Building 510, Room 2-38

    Hosted by: Niklas Mueller

    Experimental detection of fundamental symmetry violation would provide a clear signal for new physics, but theoretical predictions that can be compared with data are needed in order to interpret experimental results as measurements or constraints of beyond the Standard Model physics parameters. For low-energy experiments involving protons, neutrons, and nuclei, reliable theoretical predictions must include the strong interactions of QCD that confine quarks and gluons. I will discuss experimental searches for neutron-antineutron oscillations that test beyond the Standard Model theories of matter-antimatter asymmetry with low-scale baryon-number violation. Lattice QCD can be used to calculate the neutron-antineutron transition rate using a complete basis of six-quark operators describing neutron-antineutron oscillations in effective field theory, and I will present the first lattice QCD results for neutron-antineutron oscillations using physical quark mass simulations and fully quantified uncertainties. Other experiments searching for neutrinoless double-beta decay and dark matter direct detection use large nuclear targets that are more difficult to simulate in lattice QCD because of an exponentially difficult sign(al-to-noise) problem. I will briefly describe the state-of-the-art for lattice QCD calculations of axial, scalar, and tensor matrix elements relevant to new physics searches with nuclei and outline my ongoing efforts to improve signal-to-noise problems using phase unwrapping.

  158. RIKEN Lunch Seminar

    "On QCD and its Phase Diagram from a Functional RG Perspective"

    Presented by Mario Mitter, BNL

    Thursday, December 6, 2018, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

  159. Nuclear Theory / RIKEN Seminar

    "Novel probes of small-x QCD"

    Presented by Juan Rojo, VU University

    Friday, November 30, 2018, 2 pm
    CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    The small Bjorken-x regime of QCD is of great interest since a variety of different phenomena are known or expected to emerge, from BFKL small-x effects and non-linear and saturation dynamics to shadowing corrections in heavy nuclei. In this talk we present recent developments in our understanding of perturbative and non-perturbative QCD at small-x: the evidence for BFKL dynamics in the HERA structure function data, the precision determination of collinear PDFs from charm production at LHCb, and the first results on neural-network based fits of nuclear PDFs. We also highlight the remarkable connection between small-x QCD and high-energy astrophysics, in particular for the theoretical predictions of signal and background event rates at neutrino telescopes such as IceCube and KM3NET

  160. Nuclear Theory / RIKEN

    "Casimir effect in Yang-Mills theory"

    Presented by Dimitra Karabali, Lehman College CUNY

    Friday, November 16, 2018, 2 pm
    CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    We consider the Casimir effect in a gauge-invariant Hamiltonian formulation of nonabelian gauge theories in $(2+1)$ dimensions. We compare our analytical results with recent lattice simulations.

  161. RIKEN Lunch Seminar

    "Exclusive $\rho$ meson production in $eA$ collisions: collinear factorization and the CGC"

    Presented by Renaud Boussarie, BNL

    Thursday, November 15, 2018, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

    We will focus on the theoretical description of exclusive ρ meson production in eA collisions, using a hybrid factorization scheme which involves Balitsky's shockwave description of the Color Glass Condensate in the t channel, and Distribution Amplitudes (DAs) in the s channel. We will first give a quick introduction to the shockwave framework and to collinear factorization up to twist 3 for DAs, then we will apply these framweworks to the production of a longitudinal meson at NLO accuracy, and to the production of a transverse meson at twist 3 accuracy. We will insist on the experimental applications, and on several theoretical questions raised by our results: the dilute BFKL limit at NLO for diffraction, and collinear factorization breaking at twist 3.

  162. Nuclear Theory / RIKEN Seminar

    "Towards laboratory detection of superfluid phases of QCD"

    Presented by Ajit Srivastava, Institute of Physics, Bhubaneswar

    Friday, November 9, 2018, 2 pm
    CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    Exotic phases of QCD exhibiting strong correlations exist at very high baryon density and relatively low temperatures. Examples of such phases range from nucleon superfluid phases expected to occur in the interior of neutron stars, to possible color superconducting phases, which may occur in the core of a neutron stars. Some of these phases may also occur in relativistic heavy ion collisions in the high baryon density regime, e.g. at RHIC (BES), FAIR, and NICA. We discuss the possibilities of detecting them in heavy ion collisions focusing on the universal aspects of associated phase transitions.

  163. Nuclear Theory / RIKEN Seminar

    "Diffractive Electron-Nucleus Scattering and Ancestry in Branching Random Walks"

    Presented by Alfred Mueller, Columbia

    Friday, November 2, 2018, 2 pm
    CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

  164. RIKEN Lunch Seminar

    "DIS on "Nuclei" using holography"

    Presented by Kiminad Mamo, Stony Brook University

    Thursday, November 1, 2018, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuta Kikuchi

  165. Nuclear Theory/RIKEN Seminar

    "Studying out-of-equilibrium Quark-Gluon Plasma with QCD kinetic"

    Presented by Aleksas Mazeliauskas, University of Heidelberg

    Friday, October 19, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Niklas Mueller

    In relativistic heavy nucleus collisions an ultra-dense, high-temperature state of nuclear matter is created with de-confined quarks and gluons. Understanding how the non-equilibrium Quark-Gluon Plasma thermalizes is important in connecting the initial state physics with the emergent hydrodynamic behavior of the QGP at later times. In this talk, I will use weakly coupled QCD kinetic theory with quark and gluon degrees of freedom to study the QGP evolution in the far-from-equilibrium regime, where it exhibits universal scaling, and its approach to thermal and chemical equilibrium.

  166. RIKEN Lunch Seminar

    "Valence parton distribution function of pion using lattice"

    Presented by Nikhil Karthik, BNL

    Thursday, October 18, 2018, 12 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  167. HET/RIKEN Seminar

    "A Universally Enhanced Light-quarks Yukawa Couplings Paradigm"

    Presented by Shaouly Bar-Shalom, Technion

    Wednesday, October 10, 2018, 2:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  168. Nuclear Theory/RIKEN Seminar

    "Neutrinoless double beta decay in effective field theory"

    Presented by Jordy De Vries, UMass Amherst

    Friday, September 28, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    Next-generation neutrinoless double-beta decay experiments aim to discover lepton-number violation in order to shed light on the nature of neutrino masses. A non-zero signal would have profound implications by demonstrating the existence of elementary Majorana particles and possibly pointing towards a solution of matter-antimatter asymmetry in the universe. However, the interpretation of the experimental signal (or lack thereof) requires care. First of all, a single nonzero measurement would indicate lepton-number violation but will not identify the underlying source. Second, complicated hadronic and nuclear input is required to connect the experimental data to a fundamental description of lepton-number violation. In this talk, I will use effective field theories to connect neutrinoless double-beta decay measurements to the fundamental lepton-number-violating source.

  169. Nuclear Theory/RIKEN Seminar

    "Status of Pythia 8 for an Electron-Ion Collider"

    Presented by Ilkka Helenius, University of Tubingen

    Friday, September 21, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Andrey Tarasov

    Pythia 8 is a general-purpose Monte-Carlo event generator widely used to simulate high-energy proton-proton collisions at the LHC. Recently it has been extended to handle also other collision systems involving lepton and heavy-ion beams. In this seminar I will review the current Pythia 8 capabilities in processes relevant to an Electron-Ion Collider (EIC) and discuss about the projected future improvements. The relevant processes can be divided into two regions based on the virtuality of the intermediate photon: deeply inelastic scattering (DIS) at high virtualities and photoproduction at low virtualities. I will begin with an introduction of the event generation steps in Pythia 8 and then briefly discuss how the DIS processes can be simulated. Then I present our photoproduction framework and compare the results to the HERA data for charged-hadron and dijet production in lepton-proton collisions. In particular I discuss about the role of multiparton interactions in photon-proton interactions with resolved photons and how these can be constrained with the existing HERA data. Then I discuss how the same framework can be applied to ultra-peripheral heavy-ion collisions at the LHC where one can study high-energy photon-nucleus interactions in a kinematic region comparable to EIC. Finally I will show our first predictions for dijet production in these events and quantify the contribution of diffractive events according to the hard diffractionmodel that has been recently implemented into Pythia 8.

  170. RIKEN Lunch Seminar

    "Giant photocurrent in asymmetric Weyl semimetals from the helical magnetic effect"

    Presented by Yuta Kikuchi, RBRC

    Thursday, September 13, 2018, 12:30 pm
    Building 510, Room 2-160

  171. Joint BNL/RIKEN HET Seminar

    "Higgs pair production via gluon fusion at NLO QCD"

    Presented by Julien Baglio, Tuebingen U.

    Wednesday, September 12, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    Since the discovery of a Higgs boson in 2012 at CERN, accessing its properties is one of the main goals of the Large Hadron Collider (LHC) experimental collaborations. The triple Higgs coupling in particular is a primary target as it would be a direct probe of the shape of the scalar potential at the origin of the electroweak-symmetry-breaking mechanism, and is directly accessed via the production of a pair of Higgs bosons. In this view, it is of utmost importance to reach high precision in the theoretical prediction of Higgs boson pair production cross section at the LHC. I will present in this talk the calculation of the 2-loop QCD corrections to the Higgs-pair-production cross section via gluon fusion, that is the main production mechanism, including the top-quark mass effects in the loops. It will be shown that they can be significant in the Higgs-pair-mass differential distributions.

  172. RIKEN/NT & Quantum Computing Seminar

    "Quantum Uncertainty and Quantum Computation"

    Presented by Ivan Horvath, University of Kentucky

    Thursday, September 6, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Rob Pisarski

    I will discuss the uncertainty in quantum mechanics as a property reflecting the "quantity" (measure) on the set of possible probing outcomes. This is in contrast to the commonly used "spectral distance" (metric). An unexpected insight into the nature of quantum uncertainty (and that of measure) is obtained as a result. One of the motivations for considering measure uncertainty is that it is directly relevant for assessing the efficiency of quantum computation.

  173. Special Nuclear Theory/RIKEN Lunch Seminar

    "Signal-to-noise issues in non-relativistic quantum matter: from entanglement to thermodynamics"

    Presented by Joaquin Drut, University of North Carolina

    Thursday, August 30, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Rob Pisarski

    Non-relativistic quantum matter, as realized in ultracold atomic gases, continues to be a remarkably versatile playground for many-body physics. Experimentalists have exquisite control over temperature, density, coupling, and shape of the trapping potential. Additionally, a wide range of properties can be measured: from simple ones like equations of state to more involved ones like the bulk viscosity and entanglement. The latter has received much attention due to its connection to quantum phase transitions, but it has proven extremely difficult to compute: stochastic methods display exponential signal-to-noise issues of a very similar nature as those due to the infamous sign problem affecting finite-density QCD. In this talk, I will present an algorithm that solves the signal-to-noise issue for entanglement, and I will show results for strongly interacting systems in three spatial dimensions that are the first of their kind. I will also present a few recent explorations of the thermodynamics of polarized matter and other cases that usually have a sign problem, using complexified stochastic quantization.

  174. RIKEN Lunch Seminar

    "Non-abelian symmetries and applications in tensor networks"

    Presented by Andreas Weichselbaum, BNL

    Thursday, August 23, 2018, 12:30 pm
    Building 510, Room 2-160

  175. RIKEN Lunch Seminar

    "Universality in Classical and Quantum Chaos"

    Presented by Masanori Hanada, YITP

    Thursday, August 16, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    We study the chaotic nature of classical and quantum systems. In particular, we will study the detail of the Lyapunov growth. We will show the evidence that the spectrum of Lyapunov exponents admits universal description by Random Matrix Theory, and systems dual to black holes exhibit 'strong' universality.

  176. RIKEN Lunch Seminar

    "Nucleon isovector axial charge in 2+1-flavor domain-wall QCD with physical mass"

    Presented by Shigemi Ohta, IPNS, KEK

    Thursday, August 2, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

  177. Nuclear Theory/RIKEN Seminar

    "Jets as a probe of transverse spin physics"

    Presented by Zhongbo Kang, UCLA

    Friday, July 27, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    Jets are collimated spray of hadrons that are naturally produced in high energy colliders. They are powerful probes of many different aspects of QCD dynamics. In this talk, we will demonstrate how to use jets to explore the transverse momentum dependent (TMD) physics. A novel TMD framework to deal with back-to-back two particle correlations is presented, with which we could study the Sivers asymmetry for photon+jet or dijet production in transversely polarized proton-proton collisions. At the end of the talk, we also show how jet substructure could be used to explore the TMD fragmentation functions. We expect these studies to have important applications at RHIC in the future.

  178. RIKEN Lunch Seminar/Special Nuclear Theory Seminar

    "Neutrino Scattering on Quantum Computers"

    Presented by Alessandro Roggero, University of Washington

    Thursday, July 19, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Rob Pisarski

  179. Nuclear Theory/RIKEN Seminar

    "Confronting hydrodynamic predictions with Xe-Xe heavy-ion collision data"

    Presented by Matt Luzum, Univeristy of Sao Paulo

    Friday, July 13, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    Comparing collision systems of different size, at near the same collision energy, offers us the opportunity to probe the scaling behavior and therefore the nature of the system itself. Recently, we made predictions for Xe-Xe collisions at 5.44 TeV using viscous hydrodynamic simulations, noting that the scaling from the larger Pb-Pb system is rather generic, and arguing that robust predictions can be made that do not depend on details of the model. Here we confront our predictions with measurements that were subsequently made in a short Xe-Xe run at the LHC by the ALICE, ATLAS, and CMS collaborations. We find that the predictions are largely confirmed, with small discrepancies that could point the way to a better understanding of the medium created in such collisions.

  180. RIKEN Lunch Seminar

    "Topological structures in finite temperature QCD"

    Presented by Rasmus Larsen, BNL

    Thursday, July 12, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

    We report our study on the properties of the topological structures present in the QCD medium. We use dynamical domain wall fermion configurations on lattices of size 32^3x8 and detect the topological structures through the zero modes of the overlap operator. We explicitly show that the properties of the zero modes of the QCD Dirac operator agrees well with that of calorons with non-trivial holonomy. Different profiles of the zero modes are observed, ranging from solutions that are localized in all four spacetime dimensions, to profiles that are localized in the spatial directions, and constant along the temporal extent of the lattice. This indicates towards the presence of instanton-dyons in the hot QCD medium around Tc, where the distance between dyons control the shape and extent of the zero modes.

  181. Nuclear Theory/RIKEN Seminar

    "Liouville action, high multiplicity tail and shape of proton"

    Presented by Vladimir Skokov, BNL

    Friday, June 1, 2018, 2 pm
    CFNS Seminar Room, 2-38

    Hosted by: Chun Shen

    In this talk I violate the common wisdom "one seminar — one message" and discuss two seemingly unrelated results in the framework of the dilute-dense CGC approach: the effect of spatial eccentricity of the projectile (proton) shape on the second harmonic in double-inclusive gluon production and the theoretical description of the high gluon multiplicity tail. I will show that these two superficially unrelated results in combination may lead to unexpected consequences for the phenomenology of p-A collisions.

  182. Joint Nuclear Theory/RIKEN/CFNS Seminar

    "Novel QCD Physics at an Electron-Ion Collider"

    Presented by Stanley Brodsky, SLAC National Accelerator Laboratory, Stanford University

    Friday, May 25, 2018, 10:30 am
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    An electron-ion collider can test many fundamental features of QCD for hadron and nuclear physics, including flavor-dependent antishadowing in deep inelastic electron-nucleus scattering, the breakdown of sum rules for nuclear structure functions, the role of ``hidden-color " degrees of freedom, and the effects of "color transparency" on the baryon-to-meson anomaly observed at high transverse momentum in heavy-ion collisions. I will also discuss intrinsic heavy quark phenomena and the production of exotic multiquark states at the EIC. On the theory side, I will discuss the new insights into color confinement that one obtains from light-front holography, including supersymmetric features of the meson, baryon, and tetraquark spectroscopy. The Principle of Maximum Conformality (PMC) can be used to systematically eliminate renormalization scale ambiguities and thus obtain scheme-independent pQCD predictions.

  183. HET/RIKEN Lunch Discussions

    "Localized 4-Sigma and 5-Sigma Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events"

    Friday, May 11, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Co-hosted by Christoph Lehner and Taku Izubuchi

  184. HET/RIKEN Lunch Seminar

    "Quantum Simulation from Quantum Chemistry to Quantum Chromodynamics"

    Presented by Peter Love, Tufts

    Thursday, May 10, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Mattia Bruno and Enrico Rinaldi

    Quantum simulation proposes to use future quantum computers to calculate properties of quantum systems. In the context of chemistry, the target is the electronic structure problem: determination of the electronic energy given the nuclear coordinates of a molecule. Since 2006 we have been studying quantum approaches to quantum chemical problems, and such approaches must face the challenges of high, but fixed, precision requirements, and fermion antisymmetry. I will describe several algorithmic developments in this area including improvements upon the Jordan Wigner transformation, alternatives to phase estimation, adiabatic quantum computing approaches to the electronic structure problem, methods based on sparse Hamiltonian simulation techniques and the potential for experiments realizing these algorithms in the near future. I will also briefly review work by others on the analog and digital simulation of lattice gauge theories using quantum simulators.

  185. Nuclear Theory/RIKEN Seminar

    "Exploring the QCD phase structure with functional methods"

    Presented by Bernd-Jochen Schaefer, University of Giessen

    Friday, April 27, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    QCD at finite temperature and moderate densities predicts a phase transition from a chiral symmetry broken hadronic phase to a chirally restored deconfined quark-gluon plasma phase. In this talk I report on recent progress achieved basically with functional renormalization group (FRG) methods to reveal the QCD phase structure. Two and three quark flavor FRG investigations are confronted to results obtained with effective chiral low-energy models. The importance of quantum and thermal fluctuations is demonstrated and their consequences for the experimental signatures to detect possible critical endpoints in the phase diagram are discussed.

  186. Nuclear Theory/RIKEN Seminar

    "Dense nuclear and quark matter from holography"

    Presented by Andreas Schmitt, University of Southampton

    Friday, April 6, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    QCD at large, but not asymptotically large, baryon density presents an enormous theoretical challenge because first-principle calculations are nearly impossible. Phenomenologically, dense QCD is of great interest for the interior of neutron stars, in particular after the recent detection of gravitational waves from neutron star mergers. I will discuss a holographic approach to dense matter, making use of the Sakai-Sugimoto model, which can account for both nuclear matter and quark matter and the transition between them. In particular, nucleons are implemented as instantons in the bulk, and I will discuss certain approximations for many-nucleon matter based on the flat-space instanton solution and present the resulting phase diagrams.

  187. RIKEN Lunch Seminar

    "QCD crossover at zero and non-zero baryon densities"

    Presented by Patrick Steinbrecher, BNL

    Thursday, April 5, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  188. Nuclear Theory/RIKEN Seminar

    "Correlators of twist-2 light-ray operators in the BFKL approximation"

    Presented by Ian Balitsky

    Friday, March 16, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Andrey Tarasov

    It is well known that BFKL gives anomalous dimensions of twist-2 operators of spin j in the "BFKL limit'' $g^2\righarrow 0,\omega\equiv j-1\righarrow 0,{g^2\over\omega}$ fixed. I demonstrate that such limit describes the non-local light-ray operators and present the results of calculation of two- and three-point correlation functions of these operators in this limit. The calculation is performed in ${\cal N}$=4 SYM but the result is valid in other gauge theories such as QCD.

  189. RIKEN Lunch Seminar

    "Hadronic light-by-light scattering in the muon g-2"

    Presented by Andreas Nyffeler, University of Mainz

    Thursday, March 15, 2018, 12:30 pm
    Building 510, Room 2-160

  190. Nuclear Theory/RIKEN Seminar

    "Yang-Mills action on the light front: MHV amplitudes and Wilson lines"

    Presented by Anna Stasto, Penn State

    Friday, March 9, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    The MHV action is the Yang-Mills action quantized on the light-front, where the two explicit physical gluonic degrees of freedom have been canonically transformed to a new set of fields. This transformation leads to the action with vertices being off-shell continuations of the MHV amplitudes. We show that the solution to the field transformation expressing one of the new fields in terms of the Yang-Mills field is a certain type of the Wilson line. More precisely, it is a straight infinite gauge link with a slope extending to the light-cone minus and the transverse direction. One of the consequences of that fact is that certain MHV vertices reduced partially on-shell are gauge invariant — a fact discovered before using conventional light-front perturbation theory. We also analyze the diagrammatic content of the field transformations leading to the MHV action. We found that the diagrams for the solution to the transformation (given by the Wilson line) and its inverse differ only by light-front energy denominators.

  191. Nuclear Theory/RIKEN Seminar

    "Quark / Antiquark Correlations in Heavy-Light Ion Collisions"

    Presented by Matt Sievert, LANL

    Friday, March 2, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    It has long been known that sub-nucleonic fluctuations of the energy density in the initial stages of heavy ion collisions play an important role in generating the observed distributions of particles and their flow. These energy density fluctuations are dominated by the radiation of small-x gluons which are populated to classically large occupation numbers in the wave functions of ultra-relativistic heavy ions. While these soft gluons dominate the initial conditions for the energy density, it is quark production which determines the initial conditions of other conserved charges, like flavor and baryon number. With the recent development of state-of-the art hydrodynamics codes tailored to the Beam Energy Scan which can propagate these conserved charges into the final state, it is timely and important to calculate the initial conditions of these conserved charges from first principles in QCD. In this talk, I will present new results for the spatial correlations among quarks and antiquarks produced at mid-rapidity by pair production from small-x gluons. This single-pair production mechanism, which has been studied for some time in momentum space, is the leading contribution to these correlations in coordinate space for dilute-dense collisions. As one moves from the dilute-dense regime toward the dense-dense regime, correlations due to double pair production become more important, and these correlations persist over larger length scales than the single-pair production mechanism. Over nonperturbative length scales, only the correlations from the overlap geometry remain. I will present explicit results for quark-antiquark correlations due to single pair production, and I will outline some preliminary results for the various double-pair production mechanisms. The ultimate goal of this work will be to construct a code which can initialize these conserved charges over all length scales in heavy-ion collisions.

  192. High-Energy Physics & RIKEN Theory Seminar

    "Preparing High Energy Physics Software for the Future - the Community White Paper"

    Presented by Dr. Benedikt Hegner, CERN, Switzerland

    Wednesday, February 28, 2018, 12 pm
    Seminar Room, Bldg. 725

    Hosted by: Eric Lancon

    Particle physics has an ambitious and broad experimental program for the coming decades. This program requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment into R&D of software to acquire, manage, process, and analyses the shear amounts of data to be recorded. In planning for the High Luminosity LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that their efforts complement each other. In this spirit, the High Energy Physics community has created a white paper (arXiv:1712.06982) to describe and define the R&D activities required in order to prepare for this software upgrade. This presentation describes the expected software and computing challenges, and the plans to address them that are laid out in the white paper.

  193. RIKEN Lunch Seminar

    "Drell-Yan process beyond collinear approximation"

    Presented by Stebel Tomasz, BNL

    Thursday, February 22, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  194. RIKEN Lunch Seminar

    "Biased nuclear gluon distribution from a reweighted JIMWLK small-x ensemble"

    Presented by Adrian Dumitru, Baruch College/BNL

    Thursday, February 8, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  195. Nuclear Theory/RIKEN Seminar

    "New nonperturbative scales and glueballs in confining gauge theories"

    Presented by Mohamed Anber, Lewis & Clark College

    Friday, February 2, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    Studying confining gauge theories on a circle can provide answers to some of the deepest questions about QCD. In this talk, I start by summarizing the main characteristics shared by the compactified theories and their four dimensional cousins. Next, I show that the glueball spectrum of the compactified theories is much richer than what have been thought before. In particular, new nonperturbative scales and glueballs emerge in the deep IR regime of the theory. I discuss the spectrum in the context of super Yang-Mills and show that the lightest glueball states fill a chiral supermultiplet with doubly nonperturbative binding energy. I end with possible implications of these findings for the four dimensional gauge theories.

  196. RIKEN Lunch Seminar

    "The Coulomb Branch of N=4 SYM and Its Gravity dual as a New Holographic Model to QCD"

    Presented by Kiminad Mamo, Stony Brook

    Thursday, February 1, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  197. RIKEN Lunch Seminar

    "Exact results on massless 3-flavor QCD through new anomaly matching"

    Presented by Yuya Tanizaki, RBRC

    Thursday, January 25, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    Recently, we find a new 't Hooft anomaly of massless 3-flavor QCD, and it turns out to be useful for constraining the possible chiral symmetry breaking at finite density and zero temperature. We briefly review the anomaly matching by a toy example, and show that massless 3-flavor QCD has an 't Hooft anomaly related to ''center'' and discrete axial symmetries. We also discuss its consequences on the expectation value of the special symmetry-twisting operator, which gives the phase diagram of so-called Z(3)-QCD.

  198. Nuclear Theory/RIKEN Seminar

    "Semi-inclusive jet cross sections within SCET"

    Presented by Felix Ringer, LBL

    Friday, January 19, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    We review the de nition of semi-inclusive jet functions within Soft Collinear E ective Theory (SCET) and their application to inclusive jet cross sections. We consider the fully inclusive production cross section of jets as well as several jet substructure observables in proton-proton collisions relevant for the LHC and RHIC. The corresponding semi-inclusive jet functions satisfy renormalization group (RG) equations which take the form of standard timelike DGLAP evolution equations, analogous to collinear fragmentation functions. By solving these RG equations, the resummation of potentially large single logarithms n s lnn R can be achieved. We present numerical results at NLO+NLLR accuracy and compare to the available data.

  199. RIKEN Lunch Seminar

    "World-line Approach to Chiral Kinetic Theory and the Chiral Magnetic Effect"

    Presented by Niklas Mueller, BNL

    Thursday, January 18, 2018, 12:30 pm
    Building 510, Room 1-224

    Hosted by: Enrico Rinaldi

    Experimental searches for messengers of CP- and P- odd phenomena at RHIC and LHC have attracted much interest and are a prime motivation for significant theoretical effort: Anomalous and topological effects receive important contributions from the pre-equilibrium phase of a collision and an interesting question of phenomenological relevance is how the chiral imbalance generated at early times persists through a fluctuating background of sphalerons in addition to other "non-anomalous" interactions with the QGP. To address this question, we construct a relativistic chiral kinetic theory using the world-line formulation of quantum field theory. We outline how Berry's phase arises in this framework, and how its effects can be clearly distinguished from those arising from the chiral anomaly. We further outline how this framework can be matched to classical statistical simulations at early times and to anomalous chiral hydrodynamics at late times.

  200. RIKEN Lunch Seminar

    "Three-dimensional gauge theories using lattice regularization"

    Presented by Nikhil Karthik

    Thursday, January 11, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

    Three-dimensional gauge theories with massless fermions provide a simple yet non-perturbative setting to understand why QCD has a scale, and also provide effective descriptions of condensed matter systems. Along these lines, I will present results on infra-red scaling and scale-breaking in three-dimensional QED, QCD and large-Nc theories. I will also present some preliminary results on three-dimensional QED with one flavor of fermion regulated with and without parity anomaly.

  201. Nuclear Theory/RIKEN Seminar

    "Thermodynamics of string bits"

    Presented by Sourav Raha, University of Florida

    Friday, January 5, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    We study the Hagedorn transition in the singlet sector of the simplest super-string bit model in the tensionless limit. The gauge group of our model is SU(N) and this transition takes place when N is infinite. We use orthogonality of group characters in order to calculate the partition function. At the Hagedorn temperature there is a change in the distribution of parameters that maximize this partition function. We conclude by devising a field-theoretic interpretation of the this phenomenon.

  202. Nuclear Theory/RIKEN Seminar

    "Simultaneous extraction of spin-dependent parton distributions"

    Presented by Nobuo Sato, Jlab/University of Connecticut

    Friday, December 15, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Andrey Tarasov

    In this talk, I will present a recent global QCD analysis of spin-dependent PDFs and FFs using a MC methodology by the Jefferson Angular Momentum collaboration (JAM).

  203. RIKEN Lunch Seminar

    "Pushing the boundaries of relativistic fluid dynamics"

    Presented by Jorge Noronha

    Thursday, December 7, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    For nearly a century, dissipative effects have been included in fluid dynamics using gradients of macroscopic quantities such as the temperature and fluid velocity. Recently, results from heavy ion collision experiments and explicit model calculations have pushed the boundaries of relativistic fluid dynamics towards the far-from-equilibrium regime. In this talk I will present calculations of the large order behavior of the gradient expansion, both in kinetic theory and in holography, which have demonstrated that this series has zero radius of convergence. I will discuss the role played by novel non-equilibrium attractor solutions in determining the emergence of fluid dynamic behavior in many-body systems under extreme conditions.

  204. Nuclear Theory/RIKEN seminar

    "Medium modification of jet and jet-induced medium excitation"

    Presented by Shanshan Cao, Wayne State University

    Friday, December 1, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    A coupled linear Boltzmann transport and hydrodynamics model (CoLBT-hydro) is developed for concurrent simulation of jet propagation and hydrodynamic evolution in high-energy nuclear collisions. Diverse microscopic scattering processes (elastic and inelastic) are incorporated for parton showers, and both massive and massless partons are calculated on the same footing. Energy deposition from jets into nuclear matter is treated as source term of hydrodynamic evolution. Within this CoLBT-hydro model, nuclear modification of heavy and light flavor hadrons are simultaneously described. Evidence of jet-induced medium excitation is explored with photon-triggered jets, where significant enhancement of soft hadron production is found due to energy deposition from jets.

  205. Nuclear Theory/RIKEN Seminar

    "Higher-order corrections to jet quenching"

    Presented by Yacine Mehtar-Tani, University of Washington

    Friday, November 17, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    The phenomenon of jet quenching in ultra-relativistic heavy ion collisions reveals to effect of substantial finial state interactions which cause QCD jets to lose energy to the quark-gluon plasma (QGP), mainly by induced gluon radiation. In standard analytic approaches to energy loss, jets are approximated by single partons and thus higher-order effects in the strong coupling constant are neglected. This may prove insufficient to reliably extract QGP properties at high pT, where a significant jet suppression was recently reported by the ATLAS collaboration in PbPb collisions at the LHC. In this work we explore higher-order corrections to the inclusive jet spectrum which may be sizable owing to the fact that the probability for a highly virtual parton to split in the medium increases with the jet pT. As the effective number of jet constituents increases, jets are expected to lose more energy than a single color charge. This translates into large logarithmic enhancements of higher-orders in the perturbative series, that need to be resummed. As a result we obtain a Sudakov-like suppression factor which we investigate in the leading logarithmic approximation. We note, however, that the phase space for higher-order corrections is mitigated by coherence effects that relate to the fact that, below a characteristic angular scale, the medium does not resolve the inner jet structure. In this case, the jet lose energy coherently as a single color charge, namely, the primary parton.

  206. RIKEN Lunch Seminar

    "QCD from gluon, quark, and meson correlators"

    Presented by Mario Mitter, BNL

    Thursday, November 16, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    We present non-perturbative first-principle results for quark-, gluon- and meson 1PI correlation functions of two-flavour Landau-gauge QCD in the vacuum and Yang-Mills theory at finite temperature. They are obtained by solving their Functional Renormalisation Group equations in a systematic vertex expansion, aiming at apparent convergence within a self-consistent approximation scheme. These correlation functions carry the full information about the theory and their connection to physical observables is discussed. The presented calculations represent a crucial prerequisite for quantitative first-principle studies of QCD and its phase diagram within this framework. In particular, we have computed the ghost, quark and scalar-pseudoscalar meson propagators, as well as gluon, ghost-gluon, quark-gluon, quark, quark-meson, and meson interactions and the magnetic and electric components of the gluon propagator, and the three- and four-gluon vertices. Our results stress the crucial importance of the quantitatively correct running of different vertices in the semi-perturbative regime for describing the phenomena and scales of confinement and spontaneous chiral symmetry breaking without phenomenological input. We confront our results for the correlators with lattice simulations and compare our Debye mass to hard thermal loop perturbation theory. Finally, applications to "QCD-enhanced" low-energy effective models of QCD are discussed.

  207. Nuclear Theory/RIKEN Seminar

    "Proton radius puzzle"

    Presented by Gerald Miller, University of Washington

    Friday, November 3, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

  208. RIKEN Lunch Seminar

    "Rotating Dirac fermion in Magnetic field in 1+2 and 1+3 dimensions"

    Presented by Yizhuang Liu, Stony Brook University

    Thursday, November 2, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

  209. HET/RIKEN Seminar

    "Calculation of the electric dipole moment with the gradient flow"

    Presented by Andrea Shindler, Michigan State University

    Wednesday, November 1, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  210. RIKEN Lunch Seminar

    "Approach to equilibrium of quarkonium in quark-gluon plasma"

    Presented by Xiaojun Yao, BNL

    Thursday, October 26, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    Quarkonium can be used as a probe of quark-gluon plasma (QGP) in heavy ion collisions. The production process is complicated by several factors: plasma screening effect, in-medium dissociation and recombination, cold nuclear matter effect and feed-down contributions. In this talk, I will present a set of Boltzmann transport equations that govern the in-medium evolution of the heavy quark and quarkonium system. The dissociation and recombination rates are calculated from potential non-relativistic QCD at leading order. I will explain how the system reaches equilibrium in a QGP box and show how the system evolves under a boost invariant longitudinal expansion. I will argue that the angular distribution of quarkonium probes the stages at which recombination occurs. The presented framework will be extended in future work to include other factors influencing quarkonium production.

  211. Nuclear Theory/RIKEN Seminar

    "Quantization of three-body scattering amplitude in isobar formulation"

    Presented by Maxim Mai, George Washington University

    Friday, October 20, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    In the so-called isobar parametrization the three-particle states are populated via an interacting two-particle system (resonant or non-resonant), and a spectator. Using this parametrization, we derive the isobar-spectator interaction such that the three-body Unitarity is ensured exactly. In the first part of my talk I will show the major steps of this derivation. (arXiv:1706.06118) The second part of the talk will be dedicated to the finite-volume implementation of the framework (arXiv:1709.08222). Imaginary parts in the infinite volume, dictated by Unitarity, determine the dominant power-law finite volume effects to ensure the correct 3-body quantization condition. Furthermore, various building blocks of the 3->3 amplitude in the finite volume can become singular. However, when all contributions are summed-up, only genuine 3-body singularities remain. I will demonstrate the corresponding cancellation mechanisms explicitly for the simplified case of only one S-wave isobar.

  212. RIKEN Lunch Seminar

    "Lattice QCD and Neutrino Physics"

    Presented by Aaron Meyer, HET Group

    Thursday, October 19, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    The nucleon axial form factor is a dominant contribution to systematic uncertainties in neutrino oscillation studies. The most commonly used model parametrization of the axial form factor has uncontrolled and underestimated systematic errors. First-principles computations from lattice QCD have the potential to control theory errors by disentangling the effects of nuclear corrections from the nucleon amplitudes. In this talk, I discuss fits to the axial form factor with deuterium bubble chamber data using the model-independent $z$ expansion parameterization. I then present preliminary results for a blinded lattice QCD calculation of the nucleon axial charge $g_A$ with physical light quark masses. This calculation is being done with the Highly Improved Staggered Quark (HISQ) action and 2+1+1 flavors of sea quarks.

  213. Nuclear Theory/RIKEN Seminar

    "What can we learn from flow observables in heavy-ion collisions?"

    Presented by Jacquelyn Noronha-Hostler, Rutgers University

    Thursday, October 12, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Chun Shen

    The Quark Gluon Plasma (QGP), nature's first and most perfect liquid, has been successfully reproduced in heavy-ion collisions at RHIC and the LHC. The dynamics of the QGP can be well described by relativistic viscous hydrodynamics, allowing for precise comparisons to experimental data in order to extract the properties of the QGP. While a small shear viscosity is well-established, questions still remain regarding the precise initial state, the temperature dependence of viscosity, the smallest system that displays QGP-like properties, and the equation of state at large densities. In this talk, the various flow harmonic observables are analyzed to help answer these remaining questions.

  214. Nuclear Theory/RIKEN Seminar

    "QCD on a small circle"

    Presented by Aleksey Cherman, University of Washington

    Friday, September 29, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Recent developments have shown that QCD-like theories can be engineered to remain in a confined phase when compactified on an arbitrarily small circle, where their features may be studied quantitatively in a controlled fashion. I'll explain how a non-perturbative mass gap and chiral symmetry breaking, which are both historically viewed as prototypical strong coupling effects, appear from systematic weak-coupling calculations. Then I'll describe the rich spectrum of hadronic states, including glueball, meson, and baryon resonances in the calculable small-circle context.

  215. RIKEN Lunch Seminar

    "Color Memory, Large Gauge Transformations, and Soft Theorems in Yang-Mills Theory"

    Presented by Monica Pate, Harvard University

    Thursday, September 28, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    An infinite dimensional symmetry group which governs the infrared sectors of gauge and gravity theories has been recently discovered. This symmetry can be established both from an asymptotic symmetry analysis as well as from the corresponding Ward identities which are quantum field theoretic soft theorems. Moreover, the spontaneous breaking of these symmetries induces vacuum transitions which are detectable by charged particles through the so-called memory effect. In this seminar, I will explain the precise equivalence between asymptotic symmetries, soft theorems and memory effects in the context of tree level Yang-Mills. In particular, in this context the soft gluon theorem is Ward identity of a large gauge symmetry, whose action on the vacuum can be measured from the relative color charge of colored detectors.

  216. Nuclear Theory/RIKEN Seminar

    "TMD gluon distributions for dijet production and their behavior at small x"

    Presented by Elena Petreska, NIKHEF

    Friday, September 15, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Starting from the Color Glass Condensate (CGC) cross section for dijet production in proton-nucleus collisions we derive a transverse-momentum-dependent (TMD) factorization formula for small transverse-momentum imbalance of the jets and for finite number of colors. For the eight TMD distributions appearing in the cross section we determine their operator definitions at small-x as CGC correlators of Wilson lines and we study their JIMWLK evolution. We find that at large transverse momentum the universality of TMDs gets restored. We also discuss an extension of the approach to generalized TMDs (GTMDs) that can give an insight into the angular correlations between impact parameter and dipole size in the CGC framework.

  217. RIKEN Lunch Seminar

    "Thermal Fluctuations in Hydrodynamic Simulations of QGP"

    Presented by Mayank Singh, McGill University

    Thursday, September 14, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    Multi-particle correlations measured in heavy-ion collision experiments carry info on fluctuations present in the entire evolutionary history of the system. Initial states include geometric and quantum fluctuations and are important contributors. The thermal fluctuations during the course of QGP evolution is another conceptually important source of these fluctuations and should be studied in detail. We begin by treating thermal fluctuations as a linearized perturbation on hydrodynamic background. We present a full calculation of hadronic and photonic observables including these fluctuations. Recently we have included fluctuations in our simulations in a non-perturbative manner. Progress based on this approach will be discussed.

  218. Nuclear Theory/RIKEN Seminar

    "QCD corrections to high-pT hadron production in ep scattering"

    Presented by Werner Vogelsang, Tuebingen University

    Friday, August 25, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    We discuss various cross sections and spin observables in high-pT hadron production in lepton proton collisions, with special focus on the role of perturbative QCD corrections. We present phenomenological studies relevant for present fixed-target experiments and for a future EIC.

  219. Nuclear Theory/RIKEN Seminar

    "Factorization and phenomenology for Transverse Momentum Dependent distributions"

    Presented by Ignazio Scimemi, Universidad Complutense de Madrid

    Friday, August 18, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Factorization and phenomenology for Transverse Momentum Dependent distributions Abstract: The factorization of the hadronic part of the cross sections plays a central role in our comprehension of collider physics. I will review some aspects of the factorization, like the appearence of rapidity divergences and the related subtractions and log resummation (up to higher orders in QCD perturbative expansion) in transverse momentum dependent cross sections. As an application I will describe the inclusion of the TMD formalism in an analysis of vector boson production data.

  220. RIKEN Lunch Seminar

    "Revisit the energy density and the gluon spectrum in the boost-invariant Glasma from a semi-analytic approach"

    Presented by Ming Li

    Thursday, August 17, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    In high energy heavy-ion collisions, the soft degrees of freedom at the very initial stage after the collision can be effectively represented by strong classical gluonic fields within the Color Glass Condensate framework. Understanding the space-time evolution of the system is equivalent to solving the classical Yang-Mills equations for the gluonic fields. There have been many efforts in the past two decades in numerically solving these equations. In this talk, on the contrary, I will use a semi-analytic approach that assumes the solution has the form of a power series expansion in the proper time. I will discuss the energy-momentum tensor and the gluon spectrum obtained from this approach and make comparisons with the numerical results in the literature.

  221. Nuclear Theory/RIKEN Seminar

    "Resummation of nonglobal logarithms in QCD"

    Presented by Yoshitaka Hatta, Kyoto University

    Friday, August 11, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    The large angle emission of soft gluons from QCD jets gives rise to the so-called nonglobal logarithms. In this talk I discuss the resummation of nonglobal logarithms at finite Nc with particular emphasis on its deep connection to the small-x logarithms in high energy scattering.

  222. Nuclear Theory/RIKEN Seminar

    "General formulae for dipole Wilson line correlators with the Color Glass Condensate"

    Presented by Kenji Fukushima, University of Tokyo

    Friday, August 4, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    I talk about general formulae to compute Wilson line correlators with the Color Glass Condensate approximated by the McLerran-Venugopalan model. Specifically, as an application, I explain about a perturbative expansion of the dipole correlators in terms of 1/N_c to derive fully analytical expressions. I finally discuss the validity of the large-N_c expansion by calculating the higher-order harmonics of the flow observables in the dipole model.

  223. Nuclear Theory/RIKEN Seminar

    "Holographic Pomeron: Scattering, saturation, entropy and black hole."

    Presented by Ismail Zahed, Stony Brook

    Friday, July 7, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    I will discuss the general nature of the holographic Pomeron as a quantum QCD string exchange in both flat and curved AdS space for both pp and ep collisions at either large energies or small x. This description leads naturally to the concept of wee-strings and their distribution both in rapidity and transverse space. The holographic Pomeron carries intrinsic temperature and entropy, with the latter being identical to the recently reported entanglement entropy. I will show that this non-perturbative description of the Pomeron cross over to the the perturbative one, with a phase boundary dominated by string balls, i.e. long and massive strings near their intrinsic Hagedorn temperature. These string balls lead to a distribution of large multiplicity pp events that is in agreement with the one reported for pp collisions at the LHC. I will show that at low-x, the quantum string is so entangled that very weak string self-interactions can cause it to turn to a black hole. I will suggest that low-x saturation occurs when the density of wee-strings reaches the Bekenstein bound, with a proton size that freezes with increasing rapidity.

  224. Nuclear Theory/RIKEN Seminar

    "Probing Transverse Momentum Broadening in Heavy Ion Collisions"

    Presented by Feng Yuan, LBL

    Friday, June 30, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    In this talk, we will discuss the dijet azimuthal de-correlation in relativistic heavy ion collisions as an important probe of the transverse momentum broadening effects in heavy ion collisions. We take into account both the soft gluon radiation in vacuum associated with the Sudakov logarithms and the jet PT-broadening effects in the QCD medium. We find that the Sudakov effects are dominant at the LHC, while the medium effects can play an important role at RHIC energies. This explains why the LHC experiments have not yet observed sizable PT-broadening effects in the measurement of dijet azimuthal correlations in heavy ion collisions. Future investigations at RHIC will provide a unique opportunity to study the PT-broadening effects and help to pin down the underlying mechanism for jet energy loss in a hot and dense medium.

  225. Nuclear Theory/RIKEN Seminar

    "Better fitting through (fictitious) chemistry"

    Presented by Pasi Huovinen, Uniwersytet Wroclawski

    Monday, June 19, 2017, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    One of the puzzles we have faced at the LHC is why the thermal models apparently cannot properly fit the yield of protons. I will explore how the fit improves if we assume that nucleon-antinucleon annihilations freeze-out way later than all other number changing processes or if strange particles freeze-out before non-strange particles, and how this affects the final particle distributions in hydrodynamical calculations.

  226. Nuclear Theory/RIKEN Seminar

    "Exploring the phase structure and dynamics of QCD"

    Presented by Jan Pawlowski, Heidelberg

    Friday, June 16, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    The past years have seen tremendous progress in the description of Quantum Chromodynamics at vanishing and finite temperature and density with functional approaches, such as the functional renormalisation group or Dyson-Schwinger equations. Within these approaches QCD correlation functions of quarks, gluon and hadrons are computed non-perturbatively from first principles. In the talk I will discuss results for the phase structure of QCD at finite temperature and density, as well as for thermodynamical obserables such as the pressure and the trace anomaly. The approach is also applied to baryon number fluctuations. By now functional approaches also allow for a direct computation of transport coefficients in QCD. First results concern the temperature dependence of the shear viscosity over entropy ratio in Yang-Mills theory and QCD. The talk concludes with a discussion of the further prospects for our understanding of the phase structure and dynamics of QCD.

  227. HET/RIKEN Seminars

    "Searching for New Physics with Higgs Decays"

    Presented by Daniel Stolarski, Carleton University

    Wednesday, June 14, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

  228. Nuclear Theory/RIKEN Seminar

    "Gluon structure of hadrons and nuclei"

    Presented by Phiala Shanahan, MIT

    Friday, June 9, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    I will present the results of recent lattice QCD studies of the gluon generalised form factors of both hadrons and light nuclei. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic degrees of freedom. The goal of these studies is to provide QCD predictions to be tested at an electron-ion collider (EIC) designed to access gluon structure quantities including transverse-momentum dependent distributions (TMDs) and gluon generalised parton distributions (GPDs).

  229. RIKEN Lunch Seminar

    "Anomalies and Exact Results In Massive Quantum Chromodynamics"

    Presented by Zohar Komargodski, Stony Brook

    Thursday, June 8, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

  230. Nuclear Theory/RIKEN Seminar

    "Hydrodynamic Fluctuations in Heavy Ion Collisions"

    Presented by Derek Teaney, Stony Brook

    Friday, June 2, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    We develop a set of kinetic equations for hydrodynamic fluctuations which are equivalent to nonlinear hydrodynamics with noise. The hydrokinetic equations can be coupled to existing second-order hydrodynamic codes to incorporate the physics of these fluctuations. We use the hydrokinetic equations to analyze thermal fluctuations for a Bjorken expansion, evaluating the contribution of thermal noise from the earliest moments and at late times. In the Bjorken case, the solution to the kinetic equations determines the coefficient of the first fractional power of the gradient expansion $ \sim 1/(\tau T)^{3/2}$ for the expanding system. Numerically, we find that the contribution to the longitudinal pressure from hydrodynamic fluctuations is larger than second-order hydrodynamics for typical medium parameters used to simulate heavy ion collisions. Subsequently we analyze the behaviour of hydrodynamic fluctuations of near the QCD critical point, and dilineate the relevance Kiblle-Zurek scaling relative to other physics. If time permits we will also describe how thermal fluctuations place a lower bound on the bulk viscosity of QCD. References: Y.~Akamatsu, A.~Mazeliauskas and D.~Teaney, ``A kinetic regime of hydrodynamic fluctuations and long time tails for a Bjorken expansion,'' [arXiv:1606.07742 [nucl-th]]. Y.~Akamatsu, D. Teaney, F. Yan, Y. Yin, ``Transitting the critical point,'' in progress.

  231. RIKEN Lunch Seminar

    "Mixed Anomaly and Global Consistency"

    Presented by Yuya Tanizaki, RBRC

    Thursday, May 25, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    Symmetry and topology are powerful tools to study strongly interacting dynamics. In this talk, we will see that mixed 't Hooft anomaly and global consistency strongly constrains the possible low-energy dynamics in a simple quantum mechanical example. I will briefly explain the same idea is useful to study the phase diagram of bifundamental gauge theories at finite theta angles.

  232. HET/RIKEN Seminar

    "Cosmology in Mirror Twin Higgs and Neutrinos"

    Presented by Patrick Fox, Fermilab

    Wednesday, May 24, 2017, 2 pm
    Small Seminar Room, Bldg. 510

  233. RIKEN Lunch Seminar

    "Probing quantum entanglement at the Electron Ion Collider"

    Presented by Dima Kharzeev, BNL and Stony Brook University

    Thursday, May 18, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

  234. HET/RIKEN Seminars

    "Collider and Cosmological Signatures of a Strong Electroweak Phase Transition"

    Presented by Jonathan Kozaczuk, UMass Amherst

    Wednesday, May 17, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

  235. RIKEN Lunch Seminar

    "The nucleon axial charge from Lattice QCD"

    Presented by Enrico Rinaldi, RBRC

    Thursday, May 11, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

  236. Nuclear Theory/RIKEN Seminar

    "Probing nucleon substructure with Bayesian parameter estimation"

    Presented by Scott Moreland, Duke

    Friday, May 5, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Multi-particle correlations observed in small collision systems at top LHC energies exhibit signatures which are similar to those observed in large collision systems and generally attributed to the formation of a deconfined quark-gluon plasma (QGP). This suggests that even proton-proton and proton-lead collisions may produce small droplets of QGP which translate spatial inhomogeneities into final-state momentum anisotropies. A primary challenge in testing hydrodynamic descriptions of small collision systems is in modeling the initial stages of the collision. In this talk, I discuss recent efforts to apply Bayesian methodology to parametric descriptions of initial state physics. I show that such methods can be extended to smaller length scales which include partonic degrees of freedom and glean information regarding the fluctuating nature of the proton.

  237. RIKEN Lunch Seminar

    "Lattice study of gauge theory with multiple fermion representations"

    Presented by Ethan Neil, University of Colorado, Boulder and RBRC

    Thursday, May 4, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    "There is long-standing theoretical interest in the behavior of a strongly-coupled gauge theory in the presence of multiple fermions charged under different representations of the gauge group. In addition to the question of whether generation of dynamically separated scales will occur, such theories appear commonly in UV realizations of composite Higgs models with partially composite top quarks. I will present a first lattice study of SU(4) gauge theory with fermions in each of the two lowest-lying representations, discussing the finite-temperature phase structure and low-lying spectrum. Connections to BSM physics through a particular composite Higgs model will also be made."

  238. Nuclear Theory/RIKEN Seminar

    "Analyticity in Spin and Causality in Conformal Theories"

    Presented by Simon Caron-Huot, McGill

    Friday, April 28, 2017, 2 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    The conformal bootstrap aims to calculate scaling dimensions and correlation functions in various theories, starting from general principles such as unitarity and crossing symmetry. I will explain that local operators are not independent of each other but organize into analytic functions of spin, and I will present a formula, extending a classic one due to Froissart and Gribov in the early days of Regge theory, which quantifies the consequences of this fact. Applications will include a new way to solve crossing symmetry at large spin, as well as new bounds encoding bulk locality in theories with a gravity dual. Based on 1703.00278.

  239. Nuclear Theory/RIKEN Seminar

    "Forward particle production in pA: implementing the NLO hybrid formalism"

    Presented by Tuomas Lappi, University of Jyväskylä

    Friday, April 21, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Single inclusive particle production cross sections in high energy hadron collisions at forward rapidity are an important benchmark process for the CGC picture of small x QCD. The process can be calculated in the "hybrid formalism", where a collinear large-x quark or gluon scatters off the dense color field of the target. Recent calculations at next-to-leading order in perturbation theory have not led to a stable physical result for the single inclusive cross section at high transverse momenta. The problem with these NLO calculations lies in the subtraction procedure for the soft "rapidity" divergence which must be absorbed into BK renormalization group evolution of the target. This talk discusses recent work to understand and resolve the problems with the subtraction procedure. In particular, we have recently implemented numerically the quark channel production cross section using a new rapidity factorization procedure proposed by Iancu et al. For a fixed coupling one does indeed obtain a physically meaningful cross section which is positive and reduces in a controlled way to previous leading order calculations. However, it is not yet clear how to generalize this to running coupling in a way that is fully consistent with previous leading order calculations in coordinate space.

  240. Nuclear Theory/RIKEN Seminar

    "Effect of magnetic field on flow fluctuations in"

    Presented by Ajit M. Srivvastava

    Friday, April 14, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Very strong magnetic fields can arise in non-central heavy-ion collisions at ultrarelativistic energies, which may not decay quickly in a conducting plasma. We carry out magnetohydrodynamics simulations to study the effects of this magnetic field on the evolution of the plasma and on resulting flow fluctuations. Our results show that magnetic field leads to enhancement in elliptic flow, while flow fluctuations lead to reorganization of magnetic flux resulting in a transient increase in the local magnetic field. We also show generation of vorticity arising from nontrivial dependence of magnetosonic waves on pressure gradients and magnetic field direction. Magnetic field from collision of deformed nuclei shows very nontrivial features and can lead to qualitatively new effects on plasma evolutions. We discuss possibility of dynamo effect in the presence of vortices if any exotic high baryon density QCD phases are achieved in heavy-ion collisions.

  241. Nuclear Theory/RIKEN Seminar

    "Anisotropic dissipative fluid dynamics - foundations & applications in heavy-ion physics"

    Presented by Professor Dirk Rischke, Johann Wolfgang Goethe-Universität

    Friday, April 7, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    In collisions of heavy ions at ultrarelativistic energies, a system of hot and dense strongly interacting matter is created. This matter exhibits a surprisingly strong degree of collectivity, implying a short mean free path of its constituents and, consequently, a small shear viscosity-to-entropy density ratio. This allows to describe the evolution of the system using relativistic dissipative fluid dynamics. Dissipative fluid dynamics can be understood as an expansion around local thermodynamical equilibrium, corresponding to the ideal-fluid limit where dissipative corrections are absent. A short mean free path means that this expansion is well defined and converges sufficiently rapidly. Nevertheless, in the initial stage of a heavy-ion collision, space-time gradients of the fluid-dynamical fields (energy-momentum and net-charge densities) are so large that dissipative corrections to the ideal-fluid limit can become sizable. In this situation, novel approaches to relativistic dissipative fluid dynamics are called for. One such approach is anisotropic dissipative fluid dynamics, which is based on an expansion around an anisotropic non-equilibrium state (instead of local thermodynamical equilibrium, as in conventional dissipative fluid dynamics). In this talk, I present a derivation of the equations of motion of anisotropic dissipative fluid dynamics from the Boltzmann equation, using the method of moments. I also discuss how to resolve an ambiguity to close the system of equations of motion in the case when there are no corrections to the anisotropic state which constitutes the basis of the moment expansion.

  242. A Special HET/RIKEN Lunch Seminar

    "The Road to Nuclear Physics from Standard Model"

    Presented by Zohreh Davoudi, MIT

    Thursday, April 6, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    At the core of nuclear physics is to understand complex phenomena occurring in the hottest and densest known environments in nature, and to unravel the mystery of the dark sector and other new physics possibilities. Nuclear physicists are expected to predict, with certainty, the reaction rates relevant to star evolutions and nuclear energy research, and to obtain the "standard" effects in nuclei to reveal information about the "non-standard" sector. To achieve such certainty, the field has gradually started to eliminate its reliance on the phenomenological models and has entered an era where the underlying interactions are "effectively" based on the Standard Model of particle physics, in particular Quantum Chromodynamics (QCD). The few-nucleon systems can now emerge directly from the constituent quark and gluon degrees of freedom and with only QCD interactions in play, using the numerical method of lattice QCD. Few-body observable, such as few-nucleon interactions and scattering amplitudes, as well transition amplitudes and reaction rates, have been the focus of this vastly growing field, as once obtained from QCD, and matched to effective field theories, can advance and improve the nuclear many-body calculations of exceedingly complex systems. This talk is a brief introduction to this program and its goals, with a great focus on the progress in few-body observables from QCD.

  243. RIKEN Lunch Seminar

    "The hadronic light-by-light contribution to muon g-2 from lattice QCD"

    Presented by Luchang Jin, BNL

    Thursday, March 30, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    The current measurement of muonic g-2 disagrees with the theoretical calculation by about 3 standard deviations. Hadronic vacuum polarization (HVP) and hadronic light by light (HLbL) are the two types of processes that contribute most to the theoretical uncertainty. The current value for HLbL is still given by models. We report our latest lattice calculation of hadronic light-by-light contribution to muon g-2 using our recent developed moment method. The connected diagrams and the leading disconnected diagrams are included. The calculation is performed on a 48^3 × 96 lattice with physical pion mass and 5.5 fm box size. We expect sizable finite volume and finite lattice spacing corrections to the results of these calculations which will be estimated in calculations to be carried out over the next 1-2 years.

  244. Nuclear Theory/RIKEN Seminar

    "A solitonic approach to neutron stars: The (BPS) Skyrme model"

    Presented by Carlos Naya, Durham

    Friday, March 24, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    The Skyrme model is a low energy effective field theory of strong interactions where nuclei and baryons appear as collective excitations of pionic degrees of freedom. Proposed by Tony Skyrme in the sixties, his ideas received further support when it was discovered that in the limit of the large number of colours of QCD, an effective theory of mesons arises. In the last years, there has been a revival of Skyrme's ideas and new related models, some of them with BPS bounds (topological lower energy bounds), have been proposed. It is the aim of this talk to focus on the one known as BPS Skyrme model. After a brief introduction to this BPS limit we study its application to neutron stars where we will find that high maximal masses are supported. In addition, the BPS Skyrme model allow us to perform both mean-field and exact calculations and a comparison between both approaches will be presented.

  245. Nuclear Theory/RIKEN Seminar

    "Universal Transverse Momentum Dependent Fragmentation"

    Presented by Duff Neill, LANL

    Friday, March 17, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Fragmentation is the earliest and perhaps most interesting QCD jet observable, since it directly deals with the parton-hadron duality at the end of the QCD cascade. The most basic fragmentation observables all enjoy the property of being universal, in the sense that a sufficiently energetic parton that initiates the cascade factorizes from the rest of the event, so that the underlying soft structure of the event to a good approximation does not change the fragmentation spectrum. With the luminosities and resolution of modern detectors, we can begin to study the fragmentation process in three dimensions: both the energy spectrum and the transverse fluctuations to the collinear direction of initiating hard parton. However, when one wants to study the transverse fluctuations, one becomes very sensitive to the underlying jet definition, in particular, how the collinear direction is defined. Intuitive definitions of the jet direction, like the total momentum of the jet constituents, are inherently sensitive to soft processes, and can spoil the universality of the spectrum. I will discuss how a simple change in the jet definition removes this soft sensitivity, and allows one to study the intrinsic three dimensional structure of collinear splittings, which should be process independent.

  246. RIKEN Lunch Seminar

    "TBA"

    Presented by Vladi Skokov, BNL

    Thursday, March 16, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

  247. HET/RIKEN Seminar

    "Hunting for New Leptonic Interactions at Colliders"

    Presented by Brian Shuve, SLAC

    Wednesday, March 15, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

  248. RIKEN Lunch Seminar

    "Finite-Temperature Perturbative QCD confronts Lattice"

    Presented by Thorben Graf, University of Frankfurt

    Thursday, March 9, 2017, 12:30 pm
    Building 510, Room 1-224

    Hosted by: Heikki Mantysaari

    Since decades expressions for the thermodynamic potential were calculated perturbatively at finite temperature (and density) and pushed to higher orders. I review the current status of these efforts including resummation techniques and compare them to results of lattice Monte Carlo simulations and address unanswered questions. Finally, I present results for several thermodynamic quantities within the next-to-leading order calculation of the thermodynamic potential at finite T and \mu including non-vanishing quark masses.

  249. RIKEN Lunch Seminar

    "Generalized Nambu-Goldstone theorem"

    Presented by Yoshimasa Hidaka, RIKEN

    Thursday, March 2, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    Symmetry and its spontaneous breaking are of basic importance for understanding the low energy physics in many-body systems. When a continuum symmetry is spontaneously broken, there exist a zero mode called Nambu-Goldstone (NG) mode, which is well developed in Lorentz invariant systems. In contrast, in non-Lorentz invariant systems, the NG theorem has not been well developed. In this talk, we discuss the recent progress in generalization of NG theorem in non-relativistic systems, open systems, and systems with higher form symmetries.

  250. RIKEN Lunch Seminar

    "The Kibble-Zurek scaling for the Entanglement Entropy on the scalar field in 1+1 dimension"

    Presented by Akio Tomiya, CCNU

    Monday, February 27, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    The entanglement entropy is a candidate of an entropy in Non-equilibrium physics and recently, relaxation or thermalization is studied through the entanglement entropy with quamtum quenching, which is sudden change of parameter(s) in the Hamiltonian of the system. Global quantum quench with a finite rate which crosses critical points is known to lead to universal scaling of correlation functions as functions of the quench rate. We explore scaling properties of the entanglement entropy of a subsystem of a scaler field on the lattice, harmonic chain, during a mass quench which asymptotes to finite constant values at early and late times and for which the dynamics is exactly solvable. Both for fast and slow quenches we find that the entanglement entropy has a constant term plus a term proportional to the subsystem size. For slow quenches, the constant piece is consistent with Kibble- Zurek predictions. Furthermore, the quench rate dependence of the extensive piece enters solely through the instantaneous correlation length at the Kibble-Zurek time, suggesting a new scaling hypothesis similar to that for correlation functions. This talk is based on arXiv:1702.04359.

  251. RIKEN Lunch Seminar

    "Path-integral formula for local thermal equilibrium"

    Presented by Masaru Hongo, RIKEN

    Thursday, February 23, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    Relativistic hydrodynamics is formulated based on the assumption that systems are almost in local thermal equilibrium. However, a quantum field theoretical way to handle such a locally thermalized system has not been clearly clarified. In this study, we develop a complete path-integral formulation of relativistic quantum fields in local thermal equilibrium, which brings about the emergence of thermally induced curved spacetime. The obtained path-integral formula for local thermal equilibrium enables us to derive nondissipative part of hydrodynamic constitutive relations based on symmetry arguments. As one application, we discuss a field theoretical derivation of anomalous hydrodynamics which captures the chiral magnetic/vortical effects.

  252. HET/RIKEN Seminar

    "Few-body systems in QCD"

    Presented by Raul A. Briceno, JLAB

    Wednesday, February 22, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mattia Bruno

  253. Nuclear Theory/RIKEN Seminar

    "High energy QCD at NLO"

    Presented by Michael Lublinsky, Ben-Gurion University

    Friday, February 17, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

  254. RIKEN Lunch Seminar

    "The search for gluon saturation in pA collisions and at the EIC"

    Presented by Bowen Xiao, Central China Normal University

    Thursday, February 16, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Heikki Mantysaari

    In this talk, I plan to discuss the recent theoretical progress towards the exploration of the gluon saturation phenomenon in pA collisions and at the future EIC. Two important pillars of this exploration are the single inclusive forward hadron productions and forward dijet correlations, which have both been computed up to one-loop order within the small-x factorization formalism. Complementary measurements in pA collisions and at the EIC can help us measure small-x gluon distributions and test the generalized small-x factorization. In addition, DIS diffractive dijet process is another interesting process which is sensitive to the dipole Wigner gluon distributions. This process can provide us 3D tomographic images of low-x gluons inside high energy protons and nuclei.

  255. HET/RIKEN Seminar

    "Extracting scattering observables and resonance properties from lattice QCD"

    Presented by Maxwell T. Hansen, Helmholtz Institute Mainz

    Wednesday, February 15, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mattia Bruno

  256. Nuclear Theory/RIKEN Seminar

    "What shines brighter, Glasma or Quark-Gluon Plasma?"

    Presented by Naoto Tanji, University of Heidelberg

    Friday, January 27, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Recent classical-statistical numerical simulations have established the "bottom-up" thermalization scenario of Baier et al. as the correct weak coupling effective theory for thermalization in ultrarelativistic heavy-ion collisions. I will talk on a parametric study of photon production in the various stages of this bottom-up framework to ascertain the relative contribution of the off-equilibrium "Glasma" relative to that of a thermalized Quark-Gluon Plasma. Taking into account the constraints imposed by the measured charged hadron multiplicities at RHIC and the LHC, we find that Glasma contributions are important especially for large values of the saturation scale at both energies. Furthermore, I will report on first kinetic simulations of photon production in the expanding Glasma that will quantify our estimates.

  257. RIKEN Lunch Seminar

    "From small to moderate-x: beyond the eikonal approximation"

    Presented by Andrey Tarasov, BNL

    Thursday, January 26, 2017, 12:30 pm
    Building 510, Room 1-224

    Hosted by: Hiromichi Nishimura

    In recent years significant progress has been made in our understanding of the small-x physics beyond the eikonal approximation. Rigorous analysis of the dependence on the transverse momentum helps us better understand not only physics of the Regge limit, but to connect it to the kinematic limit of the moderate-x as well. I'll describe the technique we used in calculation of TMD evolution observed in the Drell-Yan process and present some recent results.

  258. RIKEN Lunch Seminar

    "Vector mesons and chiral symmetry restoration"

    Presented by Fabian Rennecke, Heidelberg University

    Thursday, January 19, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    Vector mesons play a prominent role for the detection of chiral symmetry restoration in the quark-gluon plasma since their in-medium modifications are directly observable in dilepton spectra. However, a direct connection between their in-medium modifications and chiral symmetry restoration remains elusive. To shed some light on this, I will first address the question how chiral symmetry breaking and the light (vector) mesons emerge from the underlying quark-gluon dynamics. Then, I will present preliminary results on the in-medium spectral functions of the rho and a1 mesons obtained from analytic continuation of Euclidean two-point functions.

  259. Nuclear Theory/RIKEN Seminar

    "Going with the flow: solving sign problems in complex space"

    Presented by Paulo Bedaque, University of Maryland

    Friday, January 13, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    We discuss a new approach to solve the sign problem arising in the Monte Carlo evaluation of path integrals. It is based on deforming the contour of integration into complex space. We will argue that for conceptual and numeric reasons it may be advantageous not to use the steepest descent manifolds (thimbles). We will discuss a variety of algorithms and their application to field theories with a fermionic sign problem and to quantum mechanical models, including real time dynamics.

  260. RIKEN Lunch Seminar

    "Plasmon mass scale and linearized gauge field fluctuations in classical Yang-Mills theory"

    Presented by Jarkko Peuron, University of Jyvaskyla

    Thursday, January 12, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Heikki Mantysaari

    In this talk I discuss the determination of plasmon mass in classical real-time Yang-Mills theory on a lattice in 3 spatial dimensions. I compare 3 different methods to determine the plasmon mass : a hard thermal loop expression in terms of the particle distribution, an effective dispersion relation constructed from fields and their time derivatives, and by measuring oscillations between electric and magnetic field modes after artificially introducing a homogeneous color electric field. Due to plasma instabilities, small quantum fluctuations on top of the classical background may significantly affect the dynamics of the system. I argue for the need for a numerical calculation of a system of classical gauge fields and small linearized fluctuations in a way that keeps the separation between the two manifest. I derive and test an explicit algorithm to solve these equations on the lattice, maintaining gauge invariance and Gauss's law.

  261. Nuclear Theory/RIKEN Seminar

    "Prompt atmospheric neutrino flux and forward charm production in proton-nucleus collisions"

    Presented by Anna Stasto, Penn State

    Friday, January 6, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    The discoveries of the extraterrestrial neutrino flux by IceCube renewed interest in the precise evaluation of the background neutrinos which are produced in the atmosphere due the cosmic ray interactions. One of the most relevant processes at high energies is the charm and beauty production in proton-nucleus collisions which needs to be evaluated at very high energies where small x effects may become important. I will discuss a recent calculation of the forward charm production in pp and pA, and compare results from different models which include small x effects due to resummation and saturation. Comparison with the LHC data will be presented and nuclear effects on light nuclei will also be discussed. Finally, I will show the resulting prompt neutrino flux and its uncertainties and discuss the potential improvements.

  262. Nuclear Theory/RIKEN Seminar

    "Proton fluctuations and multi-particle rapidity correlations"

    Presented by Kevin Dusling, PRL

    Friday, December 16, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    The effect of intrinsic fluctuations of the proton saturation momentum scale on event-by-event rapidity distributions in small systems is explored. Saturation scale fluctuations generate an asymmetry in the single particle rapidity distribution in each event resulting in genuine n-particle correlations. We introduce a color domain model that naturally explains the centrality dependence of the two-particle rapidity correlations recently measured by ATLAS, constraining the probability distribution of saturation scale fluctuations in the proton. Predictions for n=4, 6 and 8 particle rapidity correlations find that the four- and eight-particle cumulant change sign at intermediate multiplicities, a signature which could be tested experimentally.

  263. HET/RIKEN Seminar

    "The Fate of Axion Stars"

    Presented by Hong Zhang, Ohio State University

    Wednesday, December 14, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

  264. Nuclear Theory/RIKEN Seminar

    "Hydrodynamics, the gradient expansion and transient modes"

    Presented by Michal Heller, Perimeter Institute

    Friday, December 9, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    I will discuss recent developments at the interplay between hydrodynamic gradient expansion and transient modes in expanding plasma.

  265. RIKEN Lunch Seminar

    "Analytic Results for Color Glass In Space-Time Coordinates"

    Presented by Rainer Fries, Texas A&M University

    Thursday, December 8, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Heikki Mantysaari

    I will start by reviewing some previous results for the McLerran-Venugopalan model for nuclear collisions solved analytically in space-time coordinates. I will then discuss some recent work on initial angular momentum in the resulting Yang-Mills system, which leads to an interesting picture of gluon flow in the event plane. I will also describe further evolution of these results in fluid dynamics. Time permitting I will touch on ongoing efforts to construct an event generator based on analytic solutions.

  266. Nuclear Theory/RIKEN Seminar

    "Squeeze Out"

    Presented by Ron Longacre, BNL

    Wednesday, December 7, 2016, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Squeeze out happen when the expanding central fireball flows around a large surface flux tube in a central Au-Au collision at RHIC. We model such an effect in a flux tube model. Two particle correlations with respect to the $v_2$ axis formed by the soft fireball particles flowing around this large flux tube is a way of measuring the effect.

  267. Nuclear Theory/RIKEN Seminar

    "Renormalization-group flow of the effective action of cosmological large-scale structures"

    Presented by Stefan Flörchinger, Heidelberg

    Friday, December 2, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    The large scale structure of the universe forms a particular type of fluid which is governed by the properties of dark matter. I discuss how one can derive renormalization group equations for the effective action that describes the statistical properties of this fluid. Taking into account in particular effective viscosity and sound velocity terms leads to an improved framework to determine density and velocity power spectra.

  268. HET/RIKEN Seminars

    "Heavy meson decays to light resonances"

    Presented by Luka Leskovec, University of Arizona

    Wednesday, November 30, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mattia Bruno

    Lattice QCD calculations of electroweak decays with single, strong-interaction-stable hadrons in the initial and final state have recently reached a high level of precision. Many phenomenologically important decays, however, involve hadronic resonances, and their naive analysis on the lattice leads to uncontrolled systematic errors. Recent theoretical developments in the finite-volume treatment of $1 \to 2$ transition matrix elements now enable us to perform rigorous lattice calculations of electroweak decays to light resonances such as the $\rho$. After presenting the Briceno-Hansen-Walker-Loud formalism, I will discuss our numerical implementation for the $D\to\rho \ell \nu$ and $B\to\rho \ell \nu$ decays, where we aim to quantify the effect of the unstable nature of the $\rho$. Our calculations are performed on a gauge ensemble with 2+1 flavors of clover fermions with a pion mass of ~320 MeV and a lattice size of ~3.6 fm.

  269. Nuclear Theory/RIKEN Seminar

    "Phase structure and dynamics of dense QCD"

    Presented by Armen Sedrakian, Frankfurt

    Friday, November 18, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    In the first part of the talk I will discuss recent computations of the transport coefficients of dense QCD from the Kubo formalism on the basis of a two-flavor model of QCD. The second part of the talk will discuss the properties of compact stars featuring color superconducting phases of dense QCD. This will include modeling of massive compact stars, neutrino cooling of such stars, and possible signatures of a phase transition within the QCD phase diagram in the X-ray data from the young neutron star in Cassiopea A.

  270. Nuclear Theory/RIKEN Seminar

    "Quantum-field-theoretical approach to shear and bulk relaxation times"

    Presented by Alina Czajka, McGill

    Thursday, November 17, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Heikki Mantysaari

    The shear and the bulk relaxation times are important ingredients of the second order hydrodynamics whose success in heavy ion phenomenology is unquestioned. Unlike viscosites themselves, field theoretical calculations of the relaxation times are hard to come by in literature, especially for the bulk relaxation time. In this talk, we report two field-theoretical analyses involving the shear and the bulk relaxation time. First, by carefully examining the analytic structure of the stress-energy tensor response functions, we have been able to derive, for the first time, a Kubo formula involving both the shear and the bulk relaxation times. Second, by evaluating the Kubo formula within the massless scalar theory, we have so far been able to calculate the shear relaxation time in a simple form. We will then show how this calculation can be extended to calculate the bulk relaxation time as well.

  271. RIKEN Lunch Seminar

    "An overview of lattice field theory applications to dark matter searches"

    Presented by Enrico Rinaldi, RBRC

    Thursday, November 10, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

  272. HET/RIKEN Seminars

    "When the Higgs meets the Top"

    Presented by Chung Kao, University of Oklahoma

    Wednesday, November 9, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

  273. Nuclear Physics & RIKEN Theory Seminar

    "Glue spin from lattice QCD"

    Presented by Yi-Bo Yang, University of Kentucky

    Friday, November 4, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    I will present the result of the glue spin in proton from the lattice QCD simulation, and also the renormalization and matching issues. The lattice calculation is carried out with valence overlap fermions on 2+1 flavor DWF gauge configurations on four lattice spacings and four volumes including an ensemble with physical values for the quark masses. The glue spin $S_G$ in the $\overline{\text{MS}}$ scheme is obtained with the 1-loop perturbative matching. I will also discuss the generic strategy and possible difficulties of calculating the glue helicity on the lattice, from the large momentum effective theory to the lattice simulations.

  274. RIKEN Lunch Seminar

    "Form Invariance, Topological Fluctuations and Mass Gap of Yang-Mills Theory"

    Presented by Yachao Qian, Stony Brook University

    Thursday, November 3, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    We study the quantum Yang-Mills theory in the presence of topologically nontrivial backgrounds. The topologically stable gauge fields are constrained by the form invariance condition and the topological properties. Obeying these constraints, the known classical solutions to the Yang-Mills equation in the 3- and 4-dimensional Euclidean spaces are recovered, and the other allowed configurations form the nontrivial topological fluctuations at quantum level. Together, they constitute the background configurations, upon which the quantum Yang-Mills theory can be constructed. We demonstrate that the theory mimics the Higgs mechanism in a certain limit and develops a mass gap at semi-classical level on a flat space with finite size or on a sphere.

  275. HET/RIKEN Seminars

    "Neutrinoless double beta decay from lattice QCD"

    Presented by Amy Nicholson, UC Berkeley

    Wednesday, November 2, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mattia Bruno

  276. Nuclear Theory/RIKEN Seminar

    "Perturbative QCD and beyond: Bose-Eitstein correlation and $v_n$ at any n"

    Presented by Genya Levin, Tel Aviv University

    Friday, October 28, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

  277. RIKEN Lunch Seminar

    "Hybrid approach to relativistic heavy-ion collisions at the RHIC BES energies"

    Presented by Chun Shen, BNL

    Thursday, October 27, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

    Using a hybrid (viscous hydrodynamics + hadronic cascade) framework, we model the bulk dynamics of relativistic heavy-ion collisions at the RHIC BES collision energies, including the effects from non-zero net baryon current and its dissipative diffusion during the evolution. The framework is in full 3+1 dimension which allows us to study the non-trivial longitudinal structure and dynamics of the collision systems, for example, the baryon stopping/transport. The collision energy dependence of hadronic chemistry, identified particle spectra, anisotropic flows, and HBT radii is studied from 200 GeV to 19.6 GeV. Effects of breaking boost-invariance, net-baryon current, and its related diffusion on hadronic observables will be addressed. Finally, flow prediction for recent d+Au collisions at the BES energies will be presented within the same framework.

  278. HET/RIKEN Seminars

    "Collider signatures of flavorful Higgs bosons"

    Presented by Stefania Gori, University of Cincinnati

    Wednesday, October 26, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

  279. Special Nuclear Theory/RIKEN seminar

    "A new relativistic viscous hydrodynamics code for high-energy heavy-ion collisions"

    Presented by Chihi Nonaka, Nagoya University, Japan

    Wednesday, October 26, 2016, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    Relativistic hydrodynamic simulations play a key role in exploring the QGP bulk property and the QCD phase transition from analyses of high-energy heavy-ion collisions at RHIC and LHC. From the intensive study based on relativistic viscous hydrodynamic models with event-by-event initial fluctuations, we can extract detailed information of the bulk feature of the QGP such as transport coefficients and the QCD equations of states. In the quantitative analyses of the QGP property, high-precision numerical treatment on the hydrodynamic calculation is important. Recently, we developed a new 3+1 dimensional relativistic viscous hydrodynamics code in Cartesian coordinates. In the algorithm, we use a Riemann solver based on the two-shock approximation which is stable under existence of large shock waves. We extend the algorithm in Cartesian coordinates to that in Milne coordinates so that we can efficiently apply it to the analyses of relativistic heavy-ion collisions. We check the correctness of the numerical algorithm by comparing numerical calculations and analytical solutions in various problems for ideal and viscous fluids. The new numerical scheme is stable even with small numerical viscosity, which is very important to discuss the physical viscosities at RHIC and LHC.

  280. RIKEN Lunch Seminar

    "Chiral magnetic effect and anomalous transport from real-time lattice simulations"

    Presented by Niklas Mueller, Heidelberg University

    Thursday, October 20, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

    We present a first-principles study of anomaly induced transport phenomena by performing real-time lattice simulations with dynamical fermions coupled simultaneously to non-Abelian SU(Nc) and Abelian U(1) gauge fields. Investigating the behavior of vector and axial currents during a sphaleron transition in the presence of an external magnetic field, we demonstrate how the interplay of the chiral magnetic and chiral separation effect leads to the formation of a propagating wave. We further analyze the dependence of the magnitude of the induced vector current and the propagation of the wave on the amount of explicit chiral symmetry breaking due to finite quark masses. Further we perform simulations using overlap-fermions for the first time in real-time, showing that in the classical statistical regime they can be related to the Wilson formulation.

  281. RIKEN Lunch Seminar

    "Kibble-Zurek dynamics and universal off-equilibrium scaling of critical cumulants in the QCD phase diagram"

    Presented by Raju Venugopalan, BNL

    Thursday, October 13, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

    We exploit the universality between the QCD critical point and the three dimensional Ising model to derive closed form expressions for non-equilibrium critical cumulants on the crossover side of the critical point. Novel expressions are obtained for the non-Gaussian Skewness and Kurtosis cumulants; our results reveal that they can differ both in magnitude and sign from equilibrium expectations. We show further that key elements of the Kibble-Zurek framework of non-equilibrium phase transitions can be employed to describe the dynamics of these critical cumulants. As a consequence, observables sensitive to critical dynamics in heavy-ion collisions are expressible as universal scaling functions and thereby provide powerful model independent guidance in searches for the QCD critical point.

  282. HET/RIKEN Seminar

    "Cannibal Dark Matter"

    Presented by Marco Farina, Rutgers University

    Wednesday, October 12, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

  283. RIKEN Lunch Seminar

    "Complex spectrum of QCD at finite density"

    Presented by Hiromichi Nishimura, RBRC

    Thursday, October 6, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

    We consider the effective action of the Polyakov loop at finite temperature and density. Using simple models, we show two novel manifestations of the sign problem in QCD: the non-hermitian transfer matrix and the complex saddle point. As a result the mass matrix associated with the Polyakov loop becomes complex, and it gives rise to damped oscillatory behavior in Polyakov loop correlation functions, which reflects oscillatory behavior in the quark-number density reminiscent of density-density correlation functions in liquids. The complex spectrum should be observable in lattice simulations of QCD and may provide a test for finite-density algorithms.

  284. RIKEN Lunch Seminar

    "Quark Polarization at Small x"

    Presented by Matt Sievert, BNL

    Thursday, September 15, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

    Parton distribution functions in the small-x limit have long been known to be dominated by gluon bremsstrahlung produced in the BFKL and BK / JIMWLK evolution mechanisms. This small-x gluon cascade generates high color-charge densities, leading to the effective semi-classical theory known as the color-glass condensate (CGC). While this unpolarized small-x evolution has been thoroughly studied, the evolution of the polarized parton distributions is much less understood. Using modern CGC techniques, we calculate the small-x evolution equations for the helicity distribution of polarized quarks. This polarized small-x evolution is quite different from the unpolarized evolution, bringing in much more complicated dynamics which transfer spin to small x. Although the quark polarization at small x is initially suppressed, strong evolution corrections substantially enhance the amount of spin at small x. By solving our equations (numerically, in the large-Nc limit), we compute the asymptotic behavior of the quark helicity at small x, and we discuss the implications of this result for the outstanding Proton Spin Puzzle.

  285. HET/RIKEN Seminar

    "Standard Model Vacuum Stability with a 125 GeV Higgs Boson"

    Presented by Stefano Di Vita, DESY

    Friday, August 12, 2016, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Pier Paolo Giardino

  286. RIKEN Lunch Seminar

    "Photon-jet Ridge at RHIC and the LHC"

    Presented by Amir Rezaeian, The Federico Santa Maria Technical University

    Thursday, August 4, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

    I will talk about inclusive prompt photon and photon-jet production in p+A collisions at RHIC and the LHC. In particular, I show that photon-jet correlations in the Color Glass Condensate (CGC) picture exhibit long-range azimuthal collimation at near-side for low transverse momenta of the produced photon and jet in high-multiplicity events. These ridge-like features are strikingly similar to the observed ridge effect for di-hadron correlations at RHIC and the LHC. I show that correlations in the relative rapidity and the relative azimuthal angle between pairs of prompt photon and jet strongly depend on the gluon saturation dynamics at small-x kinematics and such measurements can help to understand the true origin of the observed di-hadron ridge in p+A collisions, and address whether the ridge is a universal phenomenon for all two particle correlations at high energy and high multiplicity events.

  287. RIKEN Lunch Seminar

    "CME in Chiral Viscous Hydrodynamics"

    Presented by Shuzhe Shi, Indiana University

    Thursday, July 14, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Ohki

    Anomalous chiral transport processes, with the notable examples of Chiral Magnetic Effect (CME) and Chiral Magnetic Wave (CMW), are remarkable phenomena that stem from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. The heavy ion collisions, in which topological fluctuations generate chirality imbalance, and very strong magnetic fields $|\vec{\bf B}|\sim m_\pi^2$ are present during the early stage of such collisions, provide a unique environment to study these anomalous chiral transport processes. Significant experimental efforts have been made to look for signals of CME and various other signals of anomalous chiral transport effects in heavy ion collisions. Crucial for such efforts, is the theoretical development of quantitative simulations based on hydrodynamics that incorporates chiral anomaly, implements realistic initial conditions and properly accounts for possible backgrounds. We will introduce our recent progress to understand CME qualitatively, based on a 2+1D viscous hydrodynamics framework

  288. RIKEN Lunch Seminar

    "Kondo effect in QCD"

    Presented by Sho Ozaki, Keio University

    Thursday, June 30, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

    In condensed matter physics, Kondo effect is known as an enhancement of electrical resistance of impure metals with decreasing temperature/energy. This phenomenon is the first known example of asymptotic freedom in physics, which is found well before the discovery of that of QCD. Kondo effect is caused by the combination of the following ingredients: In addition to the existence of a heavy impurity, (i) Fermi surface, (ii) quantum fluctuations (loop effects), (iii) non-Abelian nature of interaction (e.g. spin-flip interaction in the case of condensed matter physics). In this talk, I will discuss Kondo effect realized in QCD. We found the characteristic behavior of Kondo effect in quark matter with heavy quark impurity. There, the color exchange interaction mediated by gluons plays the role of the third condition (iii) for the appearance of Kondo effect. Furthermore, we found a novel type of Kondo effect induced by strong magnetic fields. In addition to the fact that the magnetic field dose not affect the color degrees of freedom, dimensional reduction to 1+1 dimensions and degenerate quarks in lowest Landau level play essential role for the magnetically induced QCD Kondo effect.

  289. Nuclear/Riken Theory Committee

    "On Pressure Isotropization in Heavy-Ion Collisions"

    Presented by Bin Wu, The Ohio State University

    Friday, June 24, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    In this talk, I would like to start with a brief introduction to non-equilibrium quantum field theory in the Schwinger-Keldysh formalism. This formalism provides a systematic way to study isotropization and other time-dependent non-equilibrium (and equilibrium) phenomena in heavy-ion collisions. I shall first discuss the foundation of classical field approximations (CSA), which is an important tool to study the evolution at very early stages. It is, however, found to be non-renormalizable. This helps us understand better the applicability of such an approximation. it is now well-known that isotropization can not be established before the breakdown of the CSA. We then use another approximation, the quasi-particle approximation (the Boltzmann equation), to study the isotropization in a scalar field theory. Our result shows explicitly the importance of quantum effects. Motivated by these observations, we have been studying whether the isotropization can be reached before the dense system of gluons, produced in the collisions of two big nuclei, becomes too dilute to be studied perturbatively in the Schwinger-Keldysh formalism. Some preliminary results shall be reported.

  290. RIKEN Lunch Seminar

    "Leading log resummation in high-energy parton production in QCD matter"

    Presented by Bin Wu, The Ohio State University

    Thursday, June 23, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Oki

  291. RIKEN Lunch Seminar

    "Static and dynamic screening effect on the resonant $\alpha-\alpha$ scattering in a QED plasma"

    Presented by Xiaojun Yao, Duke University

    Thursday, June 16, 2016, 12:30 pm
    Building 510, Room 2-84

    Hosted by: Hiroshi Oki

  292. RIKEN Lunch Seminar

    "Lefschetz-thimble path integral for studying the sign problem and Silver Blaze phenomenon"

    Presented by Yuya Tanizaki, RBRC

    Thursday, May 26, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiroshi Ohki

    Recently, Picard-Lefschetz theory gets much attention in the context of the sign problem, because it enables us to study the system with the complex classical action nonperturbatively by employing the semiclassical analysis. In this seminar, after its brief introduction, I will apply it to the one-site Hubbard model. This model has a severe sign problem, which looks quite similar to that of the finite-density QCD at low temperatures. By solving this model using the Lefschetz-thimble path integral, we are trying to understand the structure of the sign problem of finite-density QCD. Especially, I give a qualitative picture (or speculation) about the early-onset problem of the baryon number density, called the baryon Silver Blaze problem. The complex Langevin method will also be discussed if time allows.

  293. Nuclear Theory/RIKEN Seminar

    "The jet quenching parameter q-hat, and its relation to the TMDPDF"

    Presented by Abhijit Majumdar, Wayne State University

    Friday, May 20, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Based on prior work by the JET collaboration, the importance of the factorization and scale evolution of the jet quenching parameter q-hat will be outlined. This will turn out to be important for both phenomenological extractions of q-hat as well as for first principle determinations on the lattice. I will argue that for jets at RHIC and LHC, q-hat does not lie within the range of Bjoerken-x where small x effects would be considered to be dominant. Given this situation, q-hat will be found to be an integral over an operator product separated in both light-cone and transverse distance, but somewhat different from a ``traditional'' TMDPDF. This new distribution will be studied at Next-to-Leading Order and the fate of non-standard divergences discussed.

  294. RIKEN Lunch Seminar

    "Kosterlitz-Thouless transition and chiral rotation in external electromagnetic field"

    Presented by Gaoqing Cao, Fudan University

    Thursday, May 19, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Daniel Pitonyak

    In 2+1 dimensional system, the most important phase transition should be of the Kosterlitz-Thouless (KT) type. We determined the KT transition temperature T_KT as well as the mass melting temperature T^* as a function of the magnetic field. It is found that the pseudogap domain T_KT < T < T^* is enlarged with increasing strength of the magnetic field. The influence of a chiral imbalanceμ_5 was also studied. We found that even a constant axial chemical potential μ_5 can lead to inverse magnetic catalysis of the KT transition temperature in 2+1 dimensions. This is actually the de Haas—van Alphen oscillation. Furthermore, we studied the QCD vacuum structure under the influence of an electromagnetic field with a nonzero second Lorentz invariant I_2=E·B. We showed that the presence of I_2 can induce neutral pion (π_0) condensation in the QCD vacuum through the electromagnetic triangle anomaly. Within the frameworks of chiral perturbation theory at leading small-momenta expansion as well as the Nambu—Jona-Lasinio model at leading 1/Nc expansion, a universal dependence of the π_0 condensate on I_2 was found. The stability of the π_0-condensed vacuum is also discussed.

  295. HET/RIKEN Seminar

    "Higgs Pair Production in Extensions of the Standard Model"

    Presented by Ramona Groeber, Roma Tre

    Wednesday, May 18, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Pier Paolo Giardino

    Higgs pair production is not only interesting as a probe of the trilinear Higgs self-coupling, but beyond the Standard Model physics can influence the Higgs pair production cross section in many different ways, for example by new couplings, new loop particles or new resonances. In this talk, I will address the question whether we could see for the first time deviations from the Standard Model in Higgs pair production assuming that no deviations were seen before. Furthermore, for certain models I will show how higher order corrections influence the cross section.

  296. Nuclear Theory/RIKEN Seminar

    "Evolution of the jet opening angle distribution in holographic plasma"

    Presented by Andrei Sadofyev, MIT

    Friday, May 13, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Energetic jets are particularly interesting probes of QGP created in heavy ion collisions. Recently a lot of progress was made in attempting to describe the jet evolution in holography. In this talk I'll present an application of a simple dual model to study the jet substructure starting with energy and angle distributions from pQCD. In particular I will show that there are two competing effects: (1) each individual jet widens as it propagates through plasma; (2) the final jet opening angle distribution becomes narrower since wider jets lose more energy and less likely to survive. So, the mean opening angle for jets with a given energy can easily shift toward smaller angles, even while every jet in the ensemble broadens.

  297. RIKEN Lunch Seminar

    "The Functional Renormalization Group Method and Delayed Magnetic Catalysis"

    Presented by Stefan Rechenberger, University of Darmstadt

    Thursday, May 12, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Daniel Pitonyak

    This talk will start with a very general introduction to the Functional Renormalization Group method, a powerful non-perturbative tool which can be applied to various problems. The second part of the talk will demonstrate this by discussing the influence of an external magnetic field on the chiral phase transition in the theory of strong interaction. The Functional Renormalization Group analysis shows that, driven by gluon dynamics, the chiral critical temperature decreases for small values of the magnetic field. For large values of the external field, however, the phase transition temperature increases.

  298. HET/RIKEN Seminar

    "Axions and Topology"

    Presented by Simon Mages, Forschungszentrum Juelich

    Wednesday, May 11, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Tomomi Ishikawa

    This talk will be centered around the calculation of the high temperature topological susceptibility in QCD. It will provide some background on our motivation from cosmology and particle physics, which is the dependence of axion physics on non-perturbative QCD. I will show our recent results on the quenched high temperature topological susceptibility and discuss difficulties with this conventional approach, which render dynamical studies unfeasible. I will also present our new approach based on formulating QCD on a non-orientable manifold, which is a promising candidate to solve issues related to topological freezing and the divergence of autocorrelations when approaching the continuum limit.

  299. Nuclear Theory/RIKEN seminar

    "Fluid dynamics for the anisotropically expanding quark-gluon plasma"

    Presented by Dennis Bazow, The Ohio State University

    Friday, May 6, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Local momentum anisotropies become large in the early stages of the quark-gluon plasma created in relativistic heavy-ion collisions, due to the extreme difference in the longitudinal and transverse expansion rates. In such situations, fluid dynamics derived from an expansion around an isotropic local equilibrium state is bound to break down. Instead, we subsume the slowest nonhydrodynamic degree of freedom (associated with the deviation from momentum isotropy) at leading order defining a local anisoptropic quasi-equilibrium state, thereby treating the longitudinal/transverse pressure anisotropy nonperturbatively. Perturbative transport equations are then derived to deal with the remaining residual momentum anisotropies creating a complete transient effective theory called viscous anisotropic hydrodynamics. This approach has been shown to dramatically outperform viscous hydrodynamics in several simplified situations for which exact solutions exits but which share with realistic expansion scenarios the problem of large dissipative currents. We will discuss the present status of applying viscous anisotropic hydrodynamics to the phenomenological description of the quark-gluon plasma in realistic expansion scenarios.

  300. RIKEN Lunch Seminar

    "Vorticity in heavy-ion collisions and cold atoms"

    Presented by Xu-Guang Huang, Fudan University

    Thursday, May 5, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Daniel Pitonyak

    Vorticity describes the local rotation of the fluid. I will talk about our recent study of the event-by-event generation of flow vorticity in heavy-ion collisions. Several special properties of the vorticity in heavy-ion collisions will be discussed, e.g., the impact parameter dependence, the collision energy dependence, the spatial distribution, the event-by-event fluctuation of the magnitude and azimuthal direction. Vorticity can drive vector and axial current in chiral quark-gluon plasma via the chiral vortical effect. I will discuss the collective gapless mode, the chiral vortical wave, emerging from CVE and its experimental implications in heavy-ion collisions. Finally, I will consider the rotating trapped cold atomic gases and show that when there is a Weyl spin-orbit coupling such cold atomic gases provide a desktop simulator of the chiral magnetic effect and chiral separation effect.

  301. HET/RIKEN Seminar

    "Calculating TMDs and DPDs on the lattice"

    Presented by Andreas Schaefer, University of Regensburg

    Wednesday, May 4, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Tomomi Ishikawa

  302. Nuclear Theory/RIKEN Seminar

    "Going with the flow: sign problem, Lefschetz thimbles and beyond"

    Presented by Gokce Basar, University of Maryland

    Friday, April 29, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Monte Carlo method, a robust way of studying field theories and many body systems, suffers from the sign problem when the action is complex. This includes an important set of problems such as most field theories, including QCD, and strong correlated electronic systems at finite density, as well as computation of real time quantities like transport coefficients. I will show that lifting the path integration to a complex manifold provides a way to ameliorate the sign problem, and introduce a new algorithm for carrying on such a computation. I will give some quantum mechanical examples with severe sign problems, including finite density of fermions and real time observables where Monte Carlo simulations can be profitably performed by this method. Finally I will discuss the 3+1d Bose gas with nonzero chemical potential.

  303. RIKEN Lunch Seminar

    "Solving QCD2"

    Presented by Alexei Tsvelik, BNL

    Thursday, April 28, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Daniel Pitonyak

    We study a (1+1)-dimensional version of the famous Nambu-Jona-Lasinio model of Quantum Chromodynamics (QCD2) both at zero and finite chemical potential. We use non- perturbative techniques (non-Abelian bosonization and Truncated Conformal Space Approach). At zero chemical potential we describe a formation of fermion three-quark (nucleons and ?-baryons) and boson (two-quark mesons, six-quark deuterons) bound states and also a formation of a topo- logically nontrivial phase. When the chemical potential exceeds the critical value, the model has a rich phase diagram which includes phases with density wave and superfluid quasi-long-range (QLR) order and also a phase of a baryon Tomonaga-Luttinger liquid (strange metal). The QLR order results as a condensation of scalar mesons (the density wave) or six-quark bound states (deuterons).

  304. HET/RIKEN Seminar

    "Heavy Higgs Resonance Dip"

    Presented by Sunghoon Jung, SLAC

    Wednesday, April 27, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Cen Zhang

    We discuss overlooked resonance shapes of heavy Higgs bosons that arise from the resonance-continuum interference with a complex phase. They include pure resonance dips and nothingness. We derive conditions under which they are produced and we modify narrow width approximation suitable for them. We then discuss how MSSM heavy Higgs searches at the LHC can be challenged and changed.

  305. Nuclear Theory/RIKEN seminar

    "A higher spin theory of neutral excitations of fractional quantum Hall fluids"

    Presented by Dam T. Son, University of Chicago

    Friday, April 22, 2016, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

  306. RIKEN Lunch Seminar

    "Color fluctuation phenomena in high energy hadron & photon-A collisions"

    Presented by Mark Strikman, Penn State University

    Thursday, April 21, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Daniel Pitonyak

    Compositeness of the bound states and the Lorentz slowing down of high energy interactions in QED and QCD lead to emergence of new coherent phenomena. We focus on the phenomena related to the fluctuations of the strength of interaction (color fluctuations phenomena). First we consider gross violations of the Glauber model for centrality dependence of production of the leading jets in pA scattering predicted earlier within QCD and recent evidence for this phenomenon from the studies of hard pA collisions at the LHC and dAu collisions at RHIC. Color fluctuations also explain a large suppression of the cross section of coherent vector meson photoproduction as compared to the Glauber model observed recently in the ultraperipheral collisions at LHC. We outline perspectives of future studies of the color fluctuation phenomenon in ultraperipheral heavy ion collisions at the LHC and electron - nucleus colliders.

  307. Nuclear Theory/RIKEN seminar

    "Vorticular fluid and Lambda Polarization in High-energy Heavy-ion Collisions"

    Presented by Xin-Nian Wang, LBNL/CCNU

    Friday, April 15, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    The strongly coupled quark-gluon plasma created in high-energy heavy-ion collisions has rich vortical structures that are caused by global total orbital angular momentum and transverse evolution of longitudinal flow. Fermions (quarks in sQGP phase and baryons in the hadronic phase) in such a vorticular fluid are naturally polarized due to spin-orbital. I will discuss both local and global quark polarization and how one can use the lambda polarization in the final state to study the vortical structure and constrain the transport properties of sQGP.

  308. Nuclear Theory/RIKEN seminar

    "Studying Nucleons in Soliton Models"

    Presented by Song Shu, Stonybrook University

    Friday, April 1, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Both chiral solitons and confined solitons are discussed at finite temperatures and densities in effective models. Based on the solitons the nucleon properties are studied in thermal medium. The nucleon mass in medium is carefully calculated. It is showed that the chiral solitons could even survive after the chiral phase transition, while confined solitons collapse after the system is deconfined.

  309. RIKEN Lunch Seminar

    "Sphalerons Far From Equilibrium and Associated Phenomena"

    Presented by Mark Mace, Stony Brook University

    Thursday, March 31, 2016, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    In this talk, I will present a first computation of sphalerons in the glasma; the highly occupied, weakly coupled gluon dominated pre-equilibrium matter created at early times after an ultra-relativistic heavy ion collisions. The sphaleron transition is a well known ingredient in the generation of anomalous vector current from a strong external magnetic field, the so-called Chiral Magnetic Effect. We perform classical-statistical real-time lattice simulations to study the dynamics of these topological transitions; simplifying our description by employing SU(2) gauge fields and neglecting the longitudinal expansion for this first study. I will show that the non-equilibrium sphaleron transition rate is time dependent and non-Markovian, in addition to being dominant in comparison to the thermal equilibrium sphaleron transition rate. In addition, we can measure the scaling and separation of physical scales in analogy to those from thermal equilibrium, in order to parameterize this rate and understand the approach to equilibrium. I will then demonstrate that it is the magnetic screening length, which we extract non-perturbatively, that controls this rate. Additionally, I will briefly mention studies of related anomalous transport effects that we plan on studying using this first principles classical-statistical real-time lattice technology.

  310. Special RIKEN/HET Seminar

    "Axion Phenomenology from Unquenched Lattice QCD"

    Presented by Guido Martinelli, Rome University

    Thursday, March 24, 2016, 11 am
    Large Seminar Room, Bldg. 510

    Hosted by: Hiroshi Oki

    We investigate the topological properties of Nf = 2 + 1 QCD with physical quark masses, both at zero and finite temperature. At zero temperature both finite size and finite cut-off effects have been studied by comparing the continuum extrapolated results for the topological susceptibility χ with the predictions from chiral perturbation theory. At finite temperature, we explore a region going from Tc up to around 4Tc, where continuum extrapolated results for the topological susceptibility and for the fourth moment of the topological charge distribution are obtained. While the fourth moment converges to the dilute instanton gas prediction the topological susceptibility differs strongly both in the size and in the temperature dependence. This results in a shift of the axion dark matter window of almost one order of magnitude with respect to the instanton computation.

  311. Nuclear Theory/RIKEN Seminar

    "Duality, Dimensions and Reduction on the Lattice"

    Presented by Joel Giedt, Rensselaer Polytechnic Institute

    Friday, March 18, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Montonen and Olive found evidence that a duality could exist in Yang-Mills with adjoint scalars. In this scheme, the 't Hooft-Polyakov monopole forms a gauge triplet with the photon, leading to a theory equivalent to the Georgi-Glashow model but with magnetic charge replacing electric charge. The duality is believed to be realized in N=4 super-Yang-Mills. We are pursuing numerical, nonperturbative evidence for this S-duality using our lattice formulation. Two lines of approach are being taken, which I will discuss. First, we attempt to show that there is a value of the gauge coupling for which the W boson mass is equal to the monopole mass. Second, we are relating the 't Hooft loop to the Wilson loop at this self-dual coupling. On a somewhat unrelated topic, we also discuss the determination of anomalous dimensions on the lattice. In the dual gravitational picture these correspond to masses of fields in the bulk, so that some aspects of the gauge-gravity duality could be tested by such determinations. In particular in N=4 super-Yang-Mills there are predictions for the dimensions of non-protected operators at the self-dual point, based on the superconformal bootstrap.

  312. HET/RIKEN Seminar

    ""Operator Bases and Effective Field Theories""

    Presented by Brian Henning, Yale University

    Wednesday, March 16, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Cen Zhang

  313. RIKEN Lunch Seminar

    "Investigation of anomalous dynamics and the Chiral Magnetic Effect far from equilibrium"

    Presented by Niklas Mueller, University of Heidelberg

    Thursday, March 3, 2016, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Daniel Pitonyak

    We investigate the impact of the Adler-Bell-Jackiw axial anomaly on the real-time dynamics of gauge theories in the strong field regime. By studying and comparing Abelian gauge theories, such as QED, with non-Abelian systems, we try to clarify the role of topological properties and initial conditions relevant far from equilibrium. We show that the Abelian version of the Chiral Magnetic Effect, which has been predicted in the context of ultra-relativistic heavy ion collisions, can result in non-trivial experimental signatures, which could possibly be observed in future high-intensity laser experiments. Further I will report on recent investigations of chiral production mechanisms in strong non-Abelian gauge fields and I will discuss the influence of topological objects such as sphalerons, far from equilibrium. Moreover I will show first results of the studies we have undertaken since my arrival here at BNL and discuss how the combination of these studies might be used to shed more light on the role played by anomalies in the early stages of a heavy ion collision.

  314. HET/RIKEN Seminar

    "Accurate event simulation for colliders"

    Presented by Stefan Prestel, SLAC

    Wednesday, March 2, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Cen Zhang

  315. Nuclear Theory/RIKEN Seminar

    "Real time method of thermal field theory"

    Presented by Samir Mallik, Saha Institute of Nuclear Physics

    Friday, February 26, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    I review the basic ideas of real time formulation of thermal field theory. Then I like to consider the following topics in this formulation: 1) thermal propagator for a scalar field 2) spectral representation of two-point functions for arbitrary fields 3) perturbation expansion 4) one-loop self -energy 5) dilepton production

  316. RIKEN Lunch Seminar

    "Lambda_c - N interaction from lattice QCD"

    Presented by Takaya Miyamoto, Yukawa Institute for Theoretical Physics, Kyoto University

    Thursday, February 25, 2016, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Hiroshi Oki

    Recently, a new approach to investigate hadron interactions in lattice QCD has been proposed[1] and developed extensively by the HAL QCD Collaboration[2]. This method can be easily applied to heavy baryon systems even though it is difficult to obtain experimental data of heavy baryons. We have investigated the interaction between Lambda_c and nucleon (N) from lattice QCD using the HAL QCD method. This is the first step to understand charmed-baryon interaction in lattice QCD. In this talk, we present the current status of our research project onLambda_c-N interactions as well as future prospects. This talk is based on PoS (LATTICE 2015) 090.

  317. Nuclear Theory/RIKEN Seminar

    "Lattice QCD investigations of quark transverse momentum in hadrons"

    Presented by Michael Engelhardt, New Mexico State University

    Friday, February 19, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    An ongoing program of evaluating transverse momentum dependent parton distributions (TMDs) within lattice QCD is reviewed, summarizing recent progress with respect to several challenges faced by such calculations. These lattice calculations are based on a definition of TMDs through hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for a lattice calculation. Results presented include data on the naively T-odd Sivers and Boer-Mulders effects, as well as the transversity and a worm-gear distribution. Correlating quark transverse momentum with impact parameter, one can extract quark orbital angular momentum directly,including both the Ji as well as the Jaffe-Manohar definitions.

  318. Nuclear/Riken Theory Seminar

    "The Transverse Structure of the Nucleon"

    Presented by Marc Schlegel, University of Tuebingen

    Friday, February 19, 2016, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Perturbative QCD based on the Parton Model of the nucleon is a very successful theoretical approach to describe high-energy processes at particle accelerators and colliders. In particular, parton distribution functions are key ingredients of this approach and give information on the partonic substructure of the nucleon. As such they deliver a one-dimensional picture of how the parton momenta are distributed in the nucleon. In this talk extensions of the parton model are presented which provide access to more detailed information on the dynamics of partons in the nucleon. In particular observables involving transversely polarized nucleons are discussed. They can be described in terms of dynamical quark-gluon correlations which in turn can be studied at an Electron-Ion Collider. Another extension of the parton model takes into account the intrinsic transverse motion of the partons. In this approach - called Transverse Momentum Dependent (TMD) factorization - one can study three-dimensional distributions of the parton momenta. In addition, implications of the transverse motion of gluons in the nucleon will be discussed for LHC physics.

  319. Nuclear Theory/RIKEN Seminar

    "Understanding the structure of hadrons through spin observables in hard-scattering processes"

    Presented by Daniel Pitonyak, BNL

    Friday, February 12, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Almost all of the visible matter in the universe is built from hadrons, which are composed of quarks and gluons. One of the main challenges in nuclear physics is to understand this complex internal structure. In this talk, I will discuss how hard-scattering processes that involve the spin of hadrons give us insight into aspects of their inner-workings that otherwise would be inaccessible. I will focus on phenomena that arise when hadrons carry spin transverse to their direction of motion, which allow us to examine them in 3D and analyze correlations between their quarks and gluons. I will also consider a new attempt to resolve the so-called "spin crisis" of how the proton gets its spin by looking at how much spin can be carried by small-x quarks and gluons.

  320. RIKEN Lunch Seminar

    "Kinetic regime of hydrodynamic fluctuations"

    Presented by Yukinao Akamatsu, Stony Brook University

    Thursday, February 4, 2016, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Hiroshi Ohki

    Hydrodynamics is an effective theory of systems close to equilibrium. It has been applied to description of fireballs created in the heavy-ion collisions. With growing interests in fluctuation of observables, theoretical identification of its origin is crucial. One of such origins is thermal fluctuation required by the fluctuation-dissipation theorem. In this talk, I will present a new insight into the thermal fluctuation of hydrodynamics by separating the hard and soft scales in a given background. As an illustration, we adopt the Bjorken expansion as a background. The kinetic description of hard modes allows us simple interpretation of renormalization, long-time tails, and fractional powers of derivative expansion.

  321. Nuclear Theory/RIKEN Seminar

    "New aspects of QCD dynamics at high density: Jet evolution in the QGP and wave turbulence""

    Presented by Yacine Mehtar-Tani, INT Seattle

    Friday, January 29, 2016, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    An essential feature of the parton shower that form a jet evolving in vacuum is color coherence that suppresses large angle soft gluon radiation and thus, ensuing the collimation of the jet. In the presence of dense QCD matter jet constituents suffer a rapid color randomization and thus an alteration of color coherence: as a result a medium-induced gluon cascade, that can be described by a classical Makovian process, develop at large angles with respect to the jet axis [3]. A remarkable phenomenon emerges from such a cascade: the energy spectrum (of jet constituents) exhibits a scaling behavior, akin to wave turbulence, characterized by a constant flow of energy from the forward energetic patrons towards low momentum gluons down to the temperature of the plasma where energy is dissipated [4]. This picture is in agreement with a recent CMS analysis of missing energy in asymmetric dijet events where the energy balance is recovered at large angles and very soft particles [5]. In the second part of the talk I will discuss radiative corrections to jet observables that were shown to exhibit large double logarithmic enhancements. Owing to a large separation of time scales we have shown that these large corrections can be reabsorbed in a renormalization of the jet-quenching parameter q^, preserving the probabilistic picture of the parton cascade [6]. This result leads us to question the standard viewpoints of the coupling of jets to the medium: the naive perturbative approach based on a leading order calculation and the AdS/CFT correspondence for strongly coupled plasmas. I will briefly invoke in the final part of my talk the various questions that remain to be addressed. Indeed, despite the recent progress much remains to be understood about jet fragmentation in a dense medium in order to construct a systematic and predictive approach to jet-quenching from first principles.

  322. RIKEN Lunch Seminar

    "Confinement and Chiral symmetry breaking from an Interacting Instanton-dyon ensemble for 2 colors and Nf flavors"

    Presented by Rasmus Larsen, Stony Brook University

    Thursday, January 14, 2016, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    I will present numerical results based on an interacting ensemble of instanton-dyons, that explains the connection between chiral symmetry breaking and confinement. The instanton-dyons have the nice properties to behave as monopoles at low temperatures, and as instantons at high temperatures. We will see how the scaling behavior of the instanton-dyons creates a Polyakov loop dependent potential, which forces the Polyakov loop to the confining value as the density of dyons increases at lower temperatures. For 2 flavors we find that the dominating configuration in the ensemble exhibit a chiral symmetry transition at the same temperature as the confinement transition, within accuracy. The important factor in explaining confinement and chiral symmetry breaking is the density of the Instanton-dyons.

  323. RIKEN Lunch Seminar

    "Baryon interactions from Lattice QCD by Luscher's finite volume method and HAL QCD method"

    Presented by Takumi Iritani, Stony Brook University

    Thursday, December 17, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Hiroshi Oki

    Both Luscher's finite volume method and HAL QCD method are used to analyze the hadron-hadron interaction in lattice QCD. However, some systematic discrepancies are reported between them.For example, Luscher's method shows the bound states of both deuteron and di-neutron at the heavy pion mass,while these channels are scattering states from HAL QCD method. In this talk, to understand the deviations between them, we investigate the baryon interaction from both methods with the same lattice setups.From a systematic comparison of two methods, we clarify the problems in the previous studies. We also discuss the improvement of the analyses.

  324. Nuclear Theory/RIKEN seminar

    "Evolution of gluon TMDs: from small to moderate x"

    Presented by Andrey Tarasov, Jefferson Lab

    Friday, December 11, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Recently we obtained an evolution equation for gluon TMDs, which addresses a problem of unification of different kinematic limits. It describes evolution in the whole range of Bjorken x and transverse momentum k⊥. I plan to discuss this evolution equation and show how in different kinematic regimes it yields several well-known and some previously unknown results.

  325. RIKEN Lunch Seminar

    "Phase structure of lattice QCD with Wilson and twisted-mass fermions including isospin breaking"

    Presented by Derek Horkel, University of Washington

    Thursday, December 10, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Hiroshi Oki

    As the precision frontier of particle physics continues to develop, the field of lattice QCD has risen to the challenge. Modern lattice simulations, have increasingly included light non-degenerate up and down quark masses and electromagnetism. Previously answered questions about the vacuum structure of QCD on the lattice must be reexamined when these isospin breaking effects are included. If not careful, lattice practitioners may simulate in non-physical phases which cannot be extrapolated to the continuum limit. Using chiral perturbation theory, I will discuss where these non-physical phases can arise for Wilson and twisted mass fermions. I will also explain some of the complications which arise when tuning the up and down twisted quark masses to their critical values in the presence of electromagnetism.

  326. HET/RIKEN Seminar

    "Developments in Scattering Amplitudes"

    Presented by Ulrich Schubert, MPI, Munich

    Wednesday, December 9, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  327. Nuclear Theory/RIKEN Seminar

    "Semi-classics, complex saddles and real path integrals"

    Presented by Tin Sulejmanpasic, North Carolina State University

    Friday, December 4, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    I will discuss the use of semi-classics and instanton calculus and argue that, contrary to common wisdom, complex solutions of the equations of motion are a necessary ingredient of any semi-classical expansion. In particular, I will show that without the complex solutions semi-classical expansion of supersymmetric theories cannot be reconciled with supersymmetry. This has a natural interpretation in the Picard-Lefschetz theory.

  328. HET/RIKEN Lunch Seminar

    "TBA"

    Presented by Mattia Bruno and Pier Paolo Giardino, BNL

    Friday, December 4, 2015, 12 pm
    Building 510 Room 2-160

    Hosted by: Amarjit Soni

  329. RIKEN Lunch Seminar

    "Sterile neutrino dark matter produced after the QCD phase transition"

    Presented by Louis Lello, University of Pittsburgh

    Thursday, December 3, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    Sterile neutrinos are SU(2) singlets that mix with active neutrinos via a mass matrix, its diagonalization leads to mass eigenstates that couple via standard model vertices. We study the production of sterile neutrinos in the early universe from pion decays shortly after the QCD phase transition in the absence of a lepton asymmetry. We introduce the quantum kinetic equations that describe their production, freeze out and decay and discuss the various processes that lead to their production in a wide range of temperatures assessing their feasibility as dark matter candidates. We consider the production of heavy neutrinos in the mass range < 140MeV from pion decay shortly after the QCD crossover including finite temperature corrections to the pion form factors and mass. We consider the different decay channels that allow for the production of heavy neutrinos showing that their frozen distribution functions exhibit effects from "kinematic entanglement" and argue for their viability as mixed dark matter candidates. We discuss abundance, phase space density and stability constraints and argue that heavy neutrinos with lifetime >1/H0 freeze out of local thermal equilibrium.

  330. Nuclear Theory/RIKEN Seminar

    "Transversity Distribution and Collins Fragmentation Functions with QCD Evolution"

    Presented by Alexei Prokudin, Jefferson Lab

    Friday, November 20, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    We study the transverse momentum dependent (TMD) evolution of the Collins azimuthal asymmetries in e+eâˆ' annihilations and semi-inclusive hadron production in deep inelastic scattering (SIDIS) processes. All the relevant coefficients are calculated up to the next-to-leading logarithmic (NLL) order accuracy. By applying the TMD evolution at the approximate NLL order in the Collins-Soper-Sterman (CSS) formalism, we extract transversity distributions for u and d quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in back-to-back di-hadron productions in e+eâˆ' annihilations measured by BELLE and BABAR Collaborations and SIDIS data from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results, and illustrate the unpolarized quark distribution, transversity distribution, unpolarized quark fragmentation and Collins fragmentation functions depending on the transverse momentum and the hard momentum scale. We make detailed predictions for future experiments and discuss their impact.

  331. HET/RIKEN Lunch Seminar

    "Collider Phenomenology of the Right Handed Heavy Neutrinos"

    Presented by Arindam Das, University of Alabama

    Friday, November 20, 2015, 12 pm
    Building 510 Room-2-160

    Hosted by: Amarjit Soni

    We study the collider signature of pseudo-Dirac heavy neutrinos in the inverse seesaw scenario, where the heavy neutrinos with mass at the electro-weak scale can have sizable mixings with the Standard Model neutrinos, while providing the tiny light neutrino masses by the inverse seesaw mechanism. Based on a simple, concrete model realizing the inverse seesaw scenario, we fix the model parameters so as to reproduce the neutrino oscillation data and to satisfy other experimental constraints, assuming two typical flavor structures of the model and the different types of hierarchical light neutrino mass spectra. For completeness, we also consider a general parametrization for the model parameters by introducing an arbitrary orthogonal matrix and the nonzero Dirac and Majorana phases. We perform a parameter scan to identify an allowed parameter region which satisfies all experimental constraints. With the fixed parameters, we analyze the heavy neutrino signal at the LHC through trilepton final states with large missing energy and at the ILC through a single lepton plus dijet with large missing energy.

  332. RIKEN Lunch Seminar

    "Viscous Velocity Gradient Correction to Thermal Photon Emission Rate at Strong Coupling"

    Presented by Kiminad Mamo, University of Illinois at Chicago

    Thursday, November 19, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    We compute the correction to the thermal photon emission rate in first order of shear components of fluid velocity gradients in near-equilibrium hydrodynamic plasma at strong coupling regime using the real-time Schwinger-Keldysh formalism in AdS/CFT correspondence. We find that the gradient correction to the thermal photon emission rate at strong coupling is about 0.3 - 0.4 times of the equilibrium rate.

  333. Nuclear Theory/RIKEN Seminar

    "Linearly resummed hydrodynamics from gravity"

    Presented by Yanyan Bu, Ben Gurion University of the Negev

    Friday, November 13, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Using fluid/gravity correspondence, we study all-order resummed hydrodynamics in a weakly curved spacetime. The underlying microscopic theory is a finite temperature \mathcal{N}=4 super-Yang-Mills theory at strong coupling. To linear order in the amplitude of hydrodynamic variables and metric perturbations, the fluid's stress-energy tensor is computed with derivatives of both the fluid velocity and background metric resummed to all orders. In addition to two viscosity functions, we find four curvature induced structures coupled to the fluid via new transport coefficient functions, which were referred to as gravitational susceptibilities of the fluid (GSF). We analytically compute these coefficients in the hydrodynamic limit, and then numerically up to large values of momenta. We extensively discuss the meaning of all order hydrodynamics by expressing it in terms of the memory function formalism, which is also suitable for practical simulations. We also consider Gauss-Bonnet correction in the dual gravity, which is equivalent to some 1/N corrections in the dual CFT. To leading order in the Gauss-Bonnet coupling, we find that the memory function is still vanishing.

  334. HET/RIKEN Lunch Seminar

    "Flavor physics with Lambda_b baryons"

    Presented by Stefan Meinel, RBRC/ARIZONA

    Friday, November 13, 2015, 12 pm
    Building 510 Room 2-95

    Hosted by: Amarjit Soni

  335. Joint RIKEN Lunch/HET Seminar

    "Gluon-fusion Higgs production: the final frontier"

    Presented by Elisabetta Furlan, ETH, Zurich

    Thursday, November 12, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Tomomi Ishikawa

    The gluon-fusion Higgs production cross section has been recently computed through the next-to-next-to-next to leading order (N^3LO) in QCD. This unprecedented level of accuracy is crucial to exploit fully the LHC data in the validation of the Standard Model and in the search for potential (small) deviations due to new physics. I will give an overview of the tools that we employed to achieve this result, from the framework of heavy-quark effective theories to the analytical and mathematical machinery that we developed. I will conclude with some results and future prospects.

  336. Nuclear Theory/RIKEN Seminar

    "Massless QED in three dimensions with even number of flavors"

    Presented by Rajamani Narayanan, Florida International University

    Friday, November 6, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Massless QED in three (two space and one Euclidean time) with even number of flavors does not break parity. There are analytical arguments for chiral symmetry to be spontaneously broken and some numerical evidence supporting these arguments. An interesting "open" question is the possibility of a critical number of flavors below which chiral symmetry is broken. Numerical results obtained using dynamical Wilson fermions will be presented with emphasis on the behavior of the low lying eigenvalues of the Wilson Dirac operator. Finite volume analysis will be used to obtain conclusions about the absence or presence of a chiral condensate.

  337. RIKEN Lunch Seminar

    "Neural Engineering, Healing the Brain Through Electromagnetic Stimulation"

    Presented by Adam Lichtl, Delta Brain, Inc.

    Thursday, November 5, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

  338. Nuclear Theory/RIKEN Seminar

    "Observable consequences of event-by-event fluctuations of HBT radii"

    Presented by Christopher J. Plumberg, Ohio State University

    Friday, October 30, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    One of the major lessons from the field of heavy-ion physics in the past several years has been the significance of the role played by event-by-event fluctuations in the evolution of a heavy-ion collision. Their important effects on many momentum-space observables (particle yields and spectra, anisotropic flows, etc.) have already been studied systematically, and some of the properties of their event-by-event distributions, and their consequences for the extraction of medium properties such as the specific viscosity of the quark-gluon plasma (QGP), are already known. In this talk it is pointed out that similar event-by-event fluctuations of spatiotemporal observables provide complementary constraints on our understanding of the dynamical evolution of heavy-ion collisions. The relation of Hanbury Brown-Twiss (HBT) radii extracted from ensemble-averaged correlation function measurements to the mean of their event-by-event probability distribution is clarified, and a method to experimentally determine the mean and variance of this distribution is proposed and demonstrated using an ensemble of fluctuating events generated with the viscous hydrodynamic code VISH2+1. The sensitivity of the mean and variance of the HBT radii to the specific QGP shear viscosity η/s is studied using simulations with the same code. We report sensitivity of the mean pion HBT radii and their variances to the temperature dependence of η/s near the quark-hadron transition at a level similar (10-20%) to that which was previously observed for elliptic and quadrangular flow of charged hadrons.

  339. HET/RIKEN Seminar

    "N-jettiness subtraction scheme"

    Presented by Xiaohui Liu, University of Maryland

    Wednesday, October 28, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Cen Zhang

  340. Nuclear Theory/RIKEN Seminar

    "Thermal photons from a modern hydrodynamical model of heavy ion collisions"

    Presented by Jean-Francois Paquet, Stonybrook University

    Friday, October 23, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Early fluid-dynamical calculations of direct photon spectra and momentum anisotropy were found to be systematically smaller than measurements from the RHIC and the LHC, an observation that became known as the "direct photon puzzle". I will show that the use of a modern hydrodynamical model of heavy ion collisions and of the latest photon emission rates greatly improves agreement with both ALICE and PHENIX data, supporting the idea that thermal photons are the dominant source of direct photon momentum anisotropy in heavy ion collisions. The event-by-event hydrodynamical model used includes, for the first time, both shear and bulk viscosities, along with second order couplings between the two viscosities. Calculations using different photon emission rates will be shown, including one that takes into account the effect of confinement on photon emission. The effect of both shear and bulk viscosities on the photon rates will be shown to have a measurable effect on the photon momentum anisotropy.

  341. HET/RIKEN Lunch Seminar

    "Lattice QCD applications to inclusive tau decays and related topics"

    Presented by Taku Izubuchi, BNL

    Friday, October 23, 2015, 12 pm
    Building 510 Room 2-160

    Hosted by: Amarjit Soni

  342. RIKEN Lunch Seminar

    "Walking and conformal dynamics in many-flavor QCD"

    Presented by Hiroshi Ohki, RIKEN BNL Research Center

    Thursday, October 22, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Tomomi Ishikawa

    We present our lattice results of SU(3) gauge theory with many flavors, in particular with Nf=8, as a model of a walking or conformal gauge theory. We study the scaling properties of various hadron spectra including the (pseudo)scalar, vector, and baryon channels. From the Nf dependence of the theory, possible signals of walking or conformal dynamics will be discussed.

  343. HET/RIKEN Seminar

    "Phenomenology of semileptonic B-meson decays with form factors from lattice QCD"

    Presented by Ran Zhou, Fermilab

    Wednesday, October 21, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Tomomi Ishikawa

    The exclusive semileptonic $B$-meson decays $B\to K(\pi)\ell^+\ell^-$, $B \to K(\pi)\nu\bar\nu$, and $B\to\pi\tau\nu$ are used to extract the CKM elements and probe new physics beyond Standard Model. The errors of the form factors used to be an important source of the uncertainties in the theoretical predictions. Recent developments in lattice-QCD provide more accurate form factors and enable us to have better theoretical predictions. In this talk, I will present the latest lattice-QCD results of the form factors in the semileptonic $B$-meson decays processes. In addition, I will compare the theoretical predictions and recent experimental results. The tension between the Standard Model and semileptonic $B$-meson decay experimental data will be discussed.

  344. Nuclear Theory/RIKEN Seminar

    "Next-to-leading order JIMWLK from wave function formalism"

    Presented by Yair Mulian, Ben Gurion University of the Negev

    Friday, October 16, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

  345. RIKEN Lunch Seminar

    "pQCD thermodynamics with massive quarks"

    Presented by Thorben Graf, Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität

    Thursday, October 15, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    Results for several thermodynamic quantities within the next-to-leading order calculation of the thermodynamic potential in perturbative QCD at finite temperature and chemical potential including non-vanishing quark masses are presented. These results are compared to lattice data and to higher-order optimized perturbative calculations to investigate the trend brought about by mass corrections. Furthermore, the equation of state for nonvanishing isospin density was investigated within the introduced framework and the findings are also presented.

  346. HET/RIKEN Seminar

    "The Surprising Emergent Phenomena of Perturbative QCD"

    Presented by Andrew J. Larkoski, MIT

    Wednesday, September 23, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Cen Zhang

  347. Nuclear Theory/RIKEN Seminar

    "Single inclusive particle production at NLO: revised and improved"

    Presented by Alex Kovner, University of Connecticut

    Friday, September 18, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    We discuss the recent improvement of the NLO calculation of single inclusive particle production in pA collisions within the CGC formalizm. The two points that have not been addressed previously, and are treated consistently in the current approach are the Ioffe time cutoff on the configurations that can participate in the scattering, and the careful treatment of the evolution interval.

  348. Nuclear Theory/RIKEN Seminar

    "The equation of state of QCD at finite temperature and chemical potential(s)"

    Presented by Michael Strickland, Kent State University

    Friday, September 11, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

  349. Nuclear Theory/RIKEN Seminar

    "Asymptotic freedom of gluons in the Fock space"

    Presented by Stanislaw Glazek, University of Warsaw

    Friday, September 4, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Asymptotic freedom of gluons is defined in terms of scale-dependent renormalized QCD Hamiltonian operators that act in the Fock space. These operators are calculable in a new way [1,2], by solving a double-commutator differential equation [3], where the derivative is with respect to a scale parameter defined within the renormalization group procedure for effective particles (RGPEP). The RGPEP equation and its solutions are invariant with respect to boosts and may serve as a tool in attempts to dynamically explain the parton and constituent models of hadrons in QCD. The third-order QCD solution of the RGPEP equation to be discussed [2], provides an explicit example of how asymptotic freedom of gluons is exhibited in the scale-dependence of Hamiltonians as operators in the Fock space. This example also prepares ground for the fourth-order calculations of effective strong interactions using the same RGPEP equation [3], to facilitate Hamiltonian studies of many strong-interaction processes, e.g., those that involve heavy quarkonia in relativistic motion. Applications to other sectors of the Standard Model than the strong interactions await development, while only preliminary results are currently available in the domain of precise calculations in QED[4]. [1] Dynamics of effective gluons, S. D. Glazek, Phys. Rev. D63, 116006, 29p (2001). [2] Asymptotic freedom in the front-form Hamiltonian for gluons, M. Gomez-Rocha, S. D. Glazek, arXiv:1505.06688 [hep-ph], to appear in Phys. Rev. D. [3] Perturbative formulae for relativistic interactions of effective particles, S. D. Glazek, Acta Phys. Pol. B43, 1843, 20p (2012). [4] Calculation of size for bound-state constituent

  350. RIKEN Lunch Seminar

    "Analytic solution of the Boltzmann equation in the early universe"

    Presented by Jorge Noronha, University of Sao Paulo

    Thursday, September 3, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    A general method for exactly computing the nonlinear collision term of the Boltzmann equation for a massless relativistic gas in a homogeneous and isotropic spacetime is presented. This approach is used to find an exact analytical solution of the nonlinear relativistic Boltzmann equation in a Friedmann-Robertson-Walker spacetime. This solution can be used to investigate analytically the interplay between global expansion and local thermalization in rapidly evolving systems.

  351. HET/RIKEN seminar

    "Effective Field Theory of Heavy WIMP Annihilation"

    Presented by Matthew Baumgart, Rutgers University

    Wednesday, August 26, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

  352. Special Nuclear Theory/RIKEN seminar

    "Thermodynamics and topology from lattice QCD"

    Presented by Michael Muller-Preussker, Humboldt University Berlin

    Monday, August 24, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Recent efforts to investigate the thermodynamics of lattice QCD with N_f=2+1+1 fermion degrees of freedom at realistic strange and charm quark masses and at various up and down quark mass values within the framework of Wilson twisted mass fermion discretization are discussed. Comparing with recently published results in the N_f=2 case we are going to present results for the pseudo-critical temperature and preliminary results on the way to the thermodynamic equation of state. Moreover, we would like to discuss various methods to determine the topological susceptibility as a function of the temperature.

  353. Nuclear Theory/RIKEN Seminar

    "Initial state correlations, entanglement entropy and all that"

    Presented by Michal Lublinsky, Ben Gurion University of the Negev

    Friday, August 14, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    I will discuss high energy collisions of dilute on dense systems (pA) and review some ideas about initial-state induced correlations.

  354. RIKEN Lunch Seminar

    "Discrimination of large quantum ensembles"

    Presented by Emilio Bagan, GIQ, Physics Dept., UAB, Spain and Hunter College of the CUNY

    Thursday, August 13, 2015, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Daniel Pitonyak

    "Hypothesis testing is arguably the most common and elementary task in information processing (e.g., we constantly make decisions based on incomplete information). Its quantum version, quantum state discrimination, is likewise central in quantum information processing. The talk gives an introduction to the topic, focussing on discrimination of a large amount of identically prepared systems. In this limit, a powerful bound on the error rate can be derived. In classical statistics this is know as Chernoff bound. The quantum version of the Chernoff bound will be presented and discussed."

  355. HET/RIKEN Seminar

    "Constraining Extended Higgs Sectors at the LHC and Beyond"

    Presented by Tania Robens, Technical University of Dresden

    Wednesday, August 12, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  356. Nuclear Theory/RIKEN seminar

    "Inclusive Hadron Spectra: LHC data, fragmentation, towards NNLO, and all that"

    Presented by Marco Stratmann, University of Tuebingen

    Friday, August 7, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

  357. HET/RIKEN seminar

    "Higgs coupling deviations, vacuum stability and new bosons at the TeV scale"

    Presented by Raffaele D'Agnolo, Institute for Advanced Study

    Wednesday, August 5, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

    Higgs coupling measurements can shed light on the nature of electroweak symmetry breaking. However it is not trivial to go beyond generic intuitions, such as the expectation that natural theories generate large deviations, and make precise statements. In this talk I will show in a model independent way that measuring deviations at the LHC implies the existence of new bosons between a few TeV and a few hundred TeV. This is true in general, including theories where new fermions produce the deviations.

  358. Nuclear Theory/RIKEN seminar

    "Generalized Landau-level representation for spin-1/2 fermions and its applications"

    Presented by Igor Shovkovy, Arizona State University

    Friday, July 31, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    I will discuss the recently proposed generalized Landau-level representation for charged fermions in an external magnetic field. After demonstrating its key advantages over the other existing representations, I will mention several of its applications. One of them is the quantum Hall effect in graphene, where the new representation is essential for a sufficiently detailed theoretical description, in which all the dynamical parameters are running functions of the Landau-level index. The other application is the chiral asymmetry induced in dense relativistic matter in an external magnetic field. The quantitative measure of such an asymmetry is the chiral shift parameter that measures a relative shift of the longitudinal momenta (along the direction of the magnetic field) in the dispersion relations of opposite chirality fermions. Using the language of solid state physics, the corresponding ground state of dense relativistic matter could be interpreted as a Weyl metal state. Incidentally, the exact same mechanism also works in real Dirac metals.

  359. RIKEN Lunch Seminar

    "P-odd Spectral Density at Weak Coupling: Photon Emission and Second"

    Presented by Ho-Ung Yee, University of Illinois at Chicago

    Thursday, July 30, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    The P-odd spectral density of current correlation functions appears in several physical observables which are related to chiral anomaly, and is a sensitive probe of microscopic dynamics which is less protected by symmetry alone. We discuss two examples of their appearance: photon emission and the second order transport coefficient from chiral anomaly. We describe leading order weak coupling computations for these examples.

  360. HET/RIKEN Seminar

    "Probing Charm-Yukawa at LHC, Status and Prospects"

    Presented by Kohsaku Tobioka, Weizmann Institute/Tel Aviv University

    Wednesday, July 29, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

  361. Nuclear Theory/RIKEN seminar

    "Resumming large radiative corrections in the high-energy evolution of the Color Glass Condensate"

    Presented by Edmond Iancu, CEA Saclay

    Friday, July 24, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Speren Schlichting

    The BK-JIMWLK equations describing the evolution of the Color Glass Condensate with increasing energy have recently been extended to next-to-leading order (NLO) accuracy. However, some of the NLO corrections turn out to be extremely large, since amplified by (double and single) `collinear' logarithms, i.e. logarithms of ratios of transverse momenta. This difficulty points towards the existence of large radiative corrections to all orders in $\alpha_s$, as generated by the transverse phase-space, which must be computed and resummed in order to restore the convergence of the perturbative expansion. In a couple of recent papers, we developed a resummation scheme in that sense, which achieves a complete resummation of the double-logarithmic corrections and a partial resummation of the single-logarithmic ones (including the running coupling effects). We have thus deduced a collinearly-improved version of the BK equation which includes the largest radiative corrections to all orders. To demonstrate the usefulness of this equation as a tool for phenomenology, for have used it for fits to the HERA data for electron-proton deep inelastic scattering at high energy. We have obtained excellent fits with a reduced number of free parameters and with initial conditions at low energy taken from perturbative QCD.

  362. Nuclear Theory/RIKEN seminar

    "The LPM effect in energy loss and sequential bremsstrahlung"

    Presented by Peter Arnold, University of Virginia

    Friday, July 17, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    High-energy particles passing through matter lose energy by showering via hard bremsstrahlung and pair production. At very high energy, the quantum duration of each splitting process, known as the formation time, exceeds the mean free time for collisions with the medium, leading to a significant reduction in the splitting rate, known as the Landau-Pomeranchuk-Migdal (LPM) effect. A long-standing problem in field theory has been to understand how to implement this effect in cases where the formation times of two consecutive splittings overlap. I will review why this question is interesting and discuss recent progress in the context of jet energy loss in quark-gluon plasmas.

  363. RIKEN Lunch Seminar

    "Short-distance matrix elements for D-meson mixing for 2+1 flavor lattice QCD"

    Presented by Chia Cheng Chang, University of Illinois at Urbana-Champaign

    Thursday, July 2, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Tomomi Ishikawa

  364. Nuclear Theory/RIKEN Seminar

    "Event by Event fluctuations in pQCD + saturation + hydro model: pinning down QCD matter shear viscosity in AA collisions"

    Presented by Risto Paatelainen, University of Jyvaskyla

    Friday, June 26, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    We introduce an event-by-event perturbative-QCD + saturation + hydro ("EKRT") framework for ultrarelativistic heavy-ion collisions, where we compute the produced fluctuating QCD-matter energy densities from next-to-leading order perturbative QCD using a saturation conjecture to control soft particle production, and describe the space-time evolution of the QCD matter with dissipative fluid dynamics, event by event. We perform a simultaneous comparison of the centrality dependence of hadronic multiplicities, transverse momentum spectra, and flow coefficients of the azimuth-angle asymmetries, against the LHC and RHIC measurements. We compare also the computed event-by-event probability distributions of relative fluctuations of elliptic flow, and event-plane angle correlations, with the experimental data from Pb+Pb collisions at the LHC. We show how such a systematic multi-energy and multi-observable analysis tests the initial state calculation and the applicability region of hydrodynamics, and in particular how it constrains the temperature dependence of the shear viscosity-to-entropy ratio of QCD matter in its different phases in a remarkably consistent manner.

  365. RIKEN Lunch Seminar

    "One-Flavor QCD and the Dirac Spectrum at $\theta=0$"

    Presented by Jacobus Verbaarschot, Stony Brook University

    Thursday, June 25, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    The chiral condensate of one-flavor QCD is continuous when the quark mass crosses zero. In the sector of fixed topological charge though, the chiral condensate becomes discontinuous at zero mass in the the thermodynamical limit. To reconcile these contradictory observations, we have evaluated the spectral density of the Dirac operator in the epsilon domain of one-flavor QCD. In this domain, we have obtained exact analytical expressions which show that the spectral density at $\theta = 0$ becomes a strongly oscillating function for negative quark mass with an amplitude that increases exponentially with the volume. As is the case for QCD at nonzero chemical potential, these strong oscillations invalidate the Banks-Casher formula and result in a chiral condensate that is continuous as a function of the quark mass. An additional subtlety is the effect of the topological zero modes which will be discussed as well.

  366. Nuclear Theory/RIKEN seminar

    "Jet angular broadening in Heavy-Ion collisions"

    Presented by Yacine Mehtar-Tani, University of Washington

    Friday, June 19, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    The advent of the LHC opened up new perspectives for jet-quenching physics. For the first time, high enough energies are reached in heavy-ion experiments to produced jets in large numbers, and the unprecedented detector capabilities of ALICE, ATLAS and CMS, not only extend the kinematic range for the measurements previously performed at RHIC, but also allow to explore a variety of new jet-quenching observables. In this talk, I address the question of the angular broadening of jets in the presence of a dense QCD matter. I start by discussing the fundamental mechanisms underlying the formation of gluon cascades induced by multiple interactions of high energy jets with the quark-gluon plasma. Then, the rate equation that describes the evolution of the energy and angular distribution of the in-medium gluon shower is presented and solved. Two remarkable phenomena emerge. First and foremost the energy spectrum (of jet constituents) exhibits a scaling behavior characterized by a constant flow of energy towards low momenta akin to wave turbulence. As a result, energy is rapidly transported from the energy containing partons to low momentum gluons before it dissipates into the medium. Second, medium-induced gluon cascades develop and transport energy at parametrically large angles with respect to the jet axis. This picture is in semi-quantitive agreement with a recent CMS analysis of the missing energy in asymmetric dijet events where the energy balance is recovered at large angles and very soft particles.

  367. RIKEN Lunch Seminar

    "Self-similar evolution for inverse cascade of magnetic helicity driven by the chiral anomaly"

    Presented by Yi Yin, Brookhaven National Laboratory

    Thursday, June 18, 2015, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Daniel Pitonyak

    We show by solving Maxwell's equations in the presence of chiral magnetic current that the chiral anomaly would induce the inverse cascade of magnetic helicity. We found at late time, the evolution of magnetic helicity spectrum is self-similar and axial charge decays as a power law in time. We visualize how a linked magnetic configuration would evolve into a knotted configuration in real space during such evolution.

  368. HET/RIKEN Lunch Seminar

    "Light Inflaton â€" hunting for it from CMB through the Dark Matter and down to the colliders"

    Presented by Fedor Bezrukov, RBRC/U Conn

    Friday, June 12, 2015, 12 pm
    Building 510 Room 2-95

    Hosted by: Amarjit Soni

  369. HET/RIKEN seminar

    "New physics in b—>s transitions after LHC run 1"

    Presented by Wolfgang Altmannshofer, Perimeter Institute

    Wednesday, June 10, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

    I will discuss interpretations of the recent updated angular analysis of the B->K*mu+mu- decay by the LHCb collaboration. A global fit to all relevant measurements probing the flavor changing neutral current b->s mu mu transition shows tensions with Standard Model expectations. Assuming hadronic uncertainties are estimated in a sufficiently conservative way, I will discuss the implications of the experimental results on new physics, both model independently as well as in the context of models with flavor changing Z' bosons.

  370. Nuclear Theory/RIKEN seminar

    "Novel mechanisms of charmonium suppression/enhancement in pA and AA collisions"

    Presented by Boris Kopeliovich, Universidad Tecnica Federico Santa Maria, Valparaiso

    Friday, June 5, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Charmonium production in pA collisions is known to be suppressed by shadowing and absorption. There are however nuclear effects, which enhance charmonium yield. They steeply rise with energy and seem to show up in LHC data for J/psi production in pA collisions. In the case of heavy ion collisions produced charmonia are additionally suppressed by final state interaction in the created dense medium. On the contrary to current evaluations of the melting effects caused by Debye screening, a charmonium produced with a large pT easily survives even at high temperatures. Another source of charmonium suppression, missed in previous calculations, color-exchange interactions with the medium, leads to suppression of a comparable magnitude. A quantitative comparison is performed.

  371. RIKEN Lunch Seminar

    "Non-relativistic particles in a thermal bath"

    Presented by Antonio Vairo, Munich Technical University

    Thursday, June 4, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Tomomi Ishikawa

  372. HET/RIKEN Seminar

    "Cascade Decays of a Leptophobic Boson"

    Presented by Bogdan Dobrescu, Fermilab

    Wednesday, June 3, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

  373. RIKEN Lunch Seminar

    "Dysonian dynamics of the Ginibre ensemble"

    Presented by Piotr Warchol, Jagiellonian University

    Thursday, May 21, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Tomomi Ishikawa

    I will present a study of the time evolution of Ginibre matrices whose elements undergo Brownian motion. The non-Hermitian character of the Ginibre ensemble binds the dynamics of eigenvalues to the evolution of eigenvectors in a non-trivial way, leading to a system of coupled nonlinear equations resembling those for turbulent systems. We will formulate a mathematical framework allowing simultaneous description of the flow of eigenvalues and eigenvectors, and unravel a hidden dynamics as a function of new complex variable, which in the standard description is treated as a regulator only. We shall solve the evolution equations for large matrices and demonstrate that the non-analytic behavior of the Green's functions is associated with a shock wave stemming from a Burgers-like equation describing correlations of eigenvectors. I will start by reviewing similar notions in a simpler, Hermitian setting. Joint work with Zdzislaw Burda, Jacek Grela, Maciej A. Nowak and Wojtek Tarnowski (Phys.Rev.Lett. 113 (2014) 104102).

  374. Nuclear Theory/RIKEN seminar

    "Off-shell amplitudes and their applications"

    Presented by Piotr Kotko, Pennsylvania State University

    Friday, May 15, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

  375. RIKEN Lunch Seminar

    "Geometrical scaling - a window to saturation"

    Presented by Michal Praszalowicz, Jagiellonian University

    Thursday, May 14, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    Geometrical is a consequence of a traveling wave solution of the non-linear QCD evolution equation, so called Balitski-Kovchegov equation. We shall demonstrate the existence of GS in various high energy reactions. Among different consequences of GS there is a linear rise of charged particle multiplicity (Nch) and mean transverse momentum (pT) with scattering energy. Furthermore, a correlation of meant pT and Nch is predicted to scale in a way that depends on the the way particles are produced from the volume excited in a hadron-hadron scattering. This is mostly visible in heavy ion collisions at different centralities.

  376. HET/RIKEN seminar

    "Colorless Top Partners and Naturalness"

    Presented by Gustavo Burdman, IAS/University of São Paulo

    Wednesday, May 13, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: CheinYi Chen

  377. Nuclear Theory/RIKEN Seminar

    "Solving the NLO BK equation in coordinate space"

    Presented by Tuomas Lappi, University of Jyvaskyla

    Friday, May 8, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    We present results from a numerical solution of the next-to-leading order (NLO) Balitsky-Kovchegov (BK) equation in coordinate space in the large Nc limit. We show that the solution is not stable for initial conditions that are close to those used in phenomenological applications of the leading order equation. We identify the problematic terms in the NLO kernel as being related to large logarithms of a small parent dipole size, and also show that rewriting the equation in terms of the "conformal dipole" does not remove the problem. Our results qualitatively agree with expectations based on the behavior of the linear BFKL equation.

  378. HET / Riken Lunch Seminar

    "Stealth Composite Dark Matter"

    Presented by Ethan Neil, RBRC/Colorado

    Friday, May 8, 2015, 12 pm
    Building 510 Room 2-95

    Hosted by: Amarjit Soni

  379. RIKEN Lunch Talk

    "NLO transverse momentum broadening and QCD evolution of qhat"

    Presented by Hongxi Xing, Los Alamos National Lab

    Thursday, May 7, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

  380. Nuclear Theory/RIKEN Seminar

    "Applications of Soft-Collinear Effective theory to hadronic and nuclear collisions"

    Presented by Ivan Vitev, Los Alamos National Laboratory

    Friday, May 1, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Effective field theory (EFT) is a powerful framework based on exploiting symmetries and controlled expansions for problems with a natural separation of energy or distance scales. EFTs are particularly important in QCD and nuclear physics. An effective theory of QCD, ideally suited to jet applications, is Soft-Collinear Effective Theory (SCET). Recently, first steps were taken to extend SCET and describe jet evolution in strongly-interacting matter. In this talk I will demonstrate that the newly constructed theory, called SCETG, allows us to go beyond the traditional energy loss approximation in heavy ion collisions and unify the treatment of vacuum and medium-induced parton showers. It provides quantitative control over the uncertainties associated with the implementation of the in-medim modification of hadron production cross sections and allows us to accurately constrain the coupling between the jet and the medium. I will further show how SCET and SCETG can be implemented to evaluate reconstructed jet observables, such as jet shapes.

  381. HET/RIKEN seminar

    "Higgs as a Lamp Post of New Physics"

    Presented by JiJi Fan, Syracuse

    Wednesday, April 29, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

  382. Nuclear Theory/RIKEN seminar

    "Heavy Hadrons under Extreme Conditions"

    Presented by Laura Tolos, Instituto de Ciencias del Espacio (IEEC-CSIC)

    Friday, April 24, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Hadrons under extreme conditions of density and temperature have captured the interest of particle and nuclear physicists as well as astrophysicists over the years in connection with an extensive variety of physical phenomena in the laboratory as well as in the interior of stellar objects, such as neutron stars. One of the physics goals is to understand the origin of hadron masses in the context of the spontaneous breaking of the chiral symmetry of Quantum Chromodynamics (QCD) at low energies in the non-perturbative regime and to analyze the change of the hadron masses due to partial restoration of this symmetry under extreme conditions. Lately other proper QCD symmetries have also become a matter of high interest, such as heavy-quark flavor and spin symmetries. These symmetries appear when the quark masses become larger than the typical confinement scale and they are crucial for characterizing hadrons with heavy degrees of freedom. In this talk I will address the properties of heavy hadrons under extreme conditions based on effective theories that incorporate the most appropriate scales and symmetries of QCD in each case. With the on-going and upcoming research facilities, the aim is to move from the light-quark to the heavy-quark sector and to face new challenges where heavy hadrons and new QCD symmetries will play a dominant role.

  383. Nuclear Physics & RIKEN Theory Seminar

    "Consistency of Perfect Fluidity and Jet Quenching in semi-Quark-Gluon Monopole Plasmas"

    Presented by Jiechen Xu, Columbia University

    Friday, April 17, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Abstract: We utilize a new framework, CUJET3.0, to deduce the energy and temperature dependence of jet transport parameter, q^(E>10GeV,T), from a combined analysis of available data on nuclear modification factor and azimuthal asymmetries from RHIC/BNL and LHC/CERN on high energy nuclear collisions. Extending a previous perturbative-QCD based jet energy loss model (known as CUJET2.0) with (2+1)D viscous hydrodynamic bulk evolution, this new framework includes three novel features of nonperturbative physics origin: (1) the Polyakov loop suppression of color-electric scattering (aka "semi-QGP" of Pisarski et al) and (2) the enhancement of jet scattering due to emergent magnetic monopoles near Tc (aka "magnetic scenario" of Liao and Shuryak) and (3) thermodynamic properties constrained by lattice QCD data. CUJET3.0 reduces to v2.0 at high temperatures T>400 MeV, but greatly enhances q^ near the QCD deconfinement transition temperature range. This enhancement accounts well for the observed elliptic harmonics of jets with pT>10 GeV. Extrapolating our data-constrained q^ down to thermal energy scales, E∼2 GeV, we find for the first time a remarkable consistency between high energy jet quenching and bulk perfect fluidity with η/s∼T3/q^∼0.1 near Tc.

  384. RIKEN Lunch Seminar

    "Jarzynski-type equalities in gambling: role of information in capital growth"

    Presented by Yuji Hirono, Stony Brook

    Thursday, April 16, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Tomomi Ishikawa

  385. High-Energy Physics & RIKEN Theory Seminar

    "CKM physics with lattice QCD"

    Presented by Aida El-Khadra, University of Illinois at Urbana-Champaign

    Wednesday, April 15, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chris Kelly

  386. Nuclear Theory/RIKEN seminar

    "Hydrodynamics Beyond the Gradient Expansion: Resurgence and Resummation"

    Presented by Michael Heller, Perimeter Institute

    Friday, April 10, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Consistent formulations of relativistic viscous hydrodynamics involve short lived modes, leading to asymptotic rather than convergent gradient expansions. In this talk I will consider the Mueller-Israel-Stewart theory applied to a longitudinally expanding quark-gluon plasma system and identify hydrodynamics as a universal attractor without invoking the gradient expansion. I will give strong evidence for the existence of this attractor and then show that it can be recovered from the divergent gradient expansion by Borel summation. This requires careful accounting for the short-lived modes which leads to an intricate mathematical structure known from the theory of resurgence.

  387. HET/RIKEN seminar

    "Radiation from the Dark Sector"

    Presented by Tongyan Lin, University of Chicago

    Wednesday, April 8, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

  388. Nuclear Theory/RIKEN seminar

    "Gravitational collapse, holography and hydrodynamics in extreme conditions"

    Presented by Paul Chesler, Harvard University

    Friday, April 3, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    A remarkable observation from RHIC and the LHC is that the quark-gluon plasma produced in heavy-ion collisions behaves as a strongly coupled and nearly ideal liquid. Data also suggests that the debris produced by proton-nucleus collisions can also behave as a liquid. Understanding the dynamics responsible for the rapid equilibration of such tiny droplets is an outstanding problem. In recent years holography has emerged as a powerful tool to study non-equilibrium phenomena, mapping challenging quantum dynamics onto the classical dynamics of gravitational fields in one higher dimension. In the dual gravitational description the process of quark-gluon plasma formation and equilibration maps onto the process of gravitational collapse and black hole formation. I will describe how one can apply techniques and lessons learned from numerical relativity to holography and present recent work on holographic models of high energy collisions and the applicability of hydrodynamics to tiny droplets of quark-gluon plasma.

  389. RIKEN Lunch Seminar

    "Spin-Orbit Coupling in an Unpolarized Heavy Nucleus"

    Presented by Matt Sievert, BNL

    Thursday, April 2, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Daniel Pitonyak

    The next-generation Electron-Ion Collider (EIC) will make high precision measurements of spin-dependent observables at high energies on nuclear targets. This unique nuclear physics laboratory will bring together access to the multitude of spin-spin and spin-orbit structures which can exist in hadronic targets, and the high color-charge densities which generate the most intense gluon fields permitted by quantum mechanics. The interplay between those two features gives rise to new physical mechanisms which translate these spin-orbit structures into the observed cross-sections, and it makes these mechanisms amenable to first-principles calculation. In this talk, I will discuss the spin-orbit structure of quarks within an unpolarized heavy nucleus in the quasi-classical approximation. The possibility of polarized nucleons with orbital motion inside the unpolarized nucleus generates nontrivial mixing between the spin-orbit structures of the nucleons, and the corresponding structures in the nucleus. This generic feature of a dense quasi-classical system leads to direct predictions testable at an EIC, and in principle allows direct access to the orbital angular momentum in the nucleus.

  390. HET/RIKEN Seminar

    "A Global Approach to Top-quark FCNCs"

    Presented by Gauthier Durieux, Cornell University

    Wednesday, April 1, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

  391. HET/RIKEN seminar

    "Flavored Dark Matter with Weak Scale Mediators"

    Presented by Can Kilic, The University of Texas, Austin

    Wednesday, March 25, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

    All matter in the Standard Model appears in three generations, with an intricate flavor structure the origin of which is not well understood. This motivates the question whether distinct phenomenological features arise if dark matter (DM) also has a non-trivial flavor structure. In this talk I will review the experimental signatures of this scenario. In the case of lepton-flavored DM, I will argue that the generation of a lepton asymmetry at a high energy scale can also produce a DM asymmetry, which can strongly affect the sensitivity of direct detection experiments, and I will present novel signatures that can appear at colliders and in indirect detection experiments. I will also review the case of top quark-flavored DM with a distinct collider phenomenology including final states of top pairs and missing energy as well the possibility of displaced decays.

  392. Joint NT/RIKEN Seminar

    "Flow-like behavior in small systems — Multi-parton interactions and color reconnection effects at the LHC"

    Presented by Antonio Ortiz Velasquez, National Autonomous University of Mexico

    Friday, March 20, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Soeren Schlichting

    Collectivity in high multiplicity pp and p-Pb collisions is the most unexpected discovery at the LHC, its origin is still an open question. In heavy ion collisions, collectivity is attributed to final state effects due to the presence of a hot and dense QCD medium, and it is well described by viscous hydrodynamical calculations with fluctuating initial state geometries. Surprisingly, calculations which employ hydrodynamics reproduce qualitatively well the features of p-Pb data, but, the applicability of hydro in small systems faces conceptual problems. This is not the case of other approaches which do not require a medium to be formed and also are able to reproduce qualitatively well some features of data. In this talk it will be shown that multi-parton interactions and color reconnection (CR) produce flow-like effects in high multiplicity pp collisions. A study of the transverse momentum (pT) distribution of identified hadrons as a function of the event multiplicity will be presented. This comprises studies of the average pT vs hadron mass and number of constituent quarks, and a pT differential study using the Boltzmann-Gibbs Blast-Wave model. A comparison between hydro and color reconnection calculations will be presented. In this context, the results from the same study using LHC data (pp, p-Pb and Pb-Pb collisions) will be discussed.

  393. HET/RIKEN seminar

    "Spontaneous CP violation and the strong CP problem"

    Presented by Luca Vecchi, University of Maryland

    Wednesday, March 18, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chien-Yi Chen

  394. RIKEN BNL

    "The title of my talk is "How Jets and Two-Particle Correlations Impact Our Understanding of the Quark Gluon Plasma"

    Presented by Megan Connors, Yale University

    Wednesday, March 18, 2015, 2 pm
    Building 510 Room 2-160

    Hosted by: Samuel Aronson

    Relativistic heavy ion collisions can reproduce the conditions necessary to form a hot and dense medium known as the Quark Gluon Plasma (QGP), the state of the universe immediately following the Big Bang, in which quarks and gluons are deconfined. Results from experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), which study the properties of the QGP, will be presented. This seminar will focus on two particle correlations and jet physics results in Pb-Pb and Au-Au collisions at the LHC and RHIC respectively and the prospects for such measurements at the proposed sPHENIX detector. In addition, the implications of using p-p or p-A systems as a reference for these A-A measurements will be discussed. Jets are the result of a hard scattering, which occurs early in the collision process, and probe how partons interact and lose energy in the medium. Two particle correlations are used to study jet physics and energy loss, as well as the underlying event. The interplay between the two is important for understanding how high momentum particles lose energy and for finding where that lost energy goes. To quantify the influence of the QGP on these measurements, it is important to have a good baseline measurement. A-A measurements are typically compared to expectations based on p-p collisions. Recent results from p-A collisions are used to quantify cold nuclear matter effects not captured in p-p collisions. However, p-A measurements have proven to be interesting in their own unexpected way which has implications for physics measurements at the future Electron Ion Collider.

  395. HET/RIKEN Seminar

    "The Galactic Center Gamma-ray Excess: Have We Started to See Dark Matter"

    Presented by Samuel McDermott, Stony Brook University

    Wednesday, March 4, 2015, 2 pm
    Building 510 SSR

    Hosted by: Sally Dawson

  396. High-Energy Physics & RIKEN Theory Seminar

    "The Search for Relic Neutrinos"

    Presented by Mariangela Lisanti, Princeton

    Wednesday, February 25, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  397. RIKEN/BNL Lunch Time Talk

    "Bose-Einstein Condensation, Isotropization, and Thermalization in Overpopulated Systems"

    Presented by Jinfeng Liao, Indiana University / RBRC

    Thursday, February 12, 2015, 12:30 pm
    Building 510 Room 2-160

    Hosted by: Tomomi Ishikawa

    We discuss recent progress, using the kinetic theory framework, in understanding the non-equilibrium evolution of overpopulated systems that resemble the glasma during the early stage of heavy ion collisions. We analyze a number of important factors that influence the course of thermalization in such systems, and in particular their consequences for the nontrivial dynamics driving Bose-Einstein Condensation as well as the isotropization. We discuss recent progress, using the kinetic theory framework, in understanding the non-equilibrium evolution of overpopulated systems that resemble the glasma during the early stage of heavy ion collisions. We analyze a number of important factors that influence the course of thermalization in such systems, and in particular their consequences for the nontrivial dynamics driving Bose-Einstein Condensation as well as the isotropization.

  398. High-Energy Physics & RIKEN Theory Seminar

    "Electric Dipole Moments, New Physics, and (lattice) QCD"

    Presented by Vincenzo Cirigliano, Los Alamos

    Wednesday, February 11, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    In this talk I will discuss the role of electric dipole moments (EDMs) as probes of physics beyond the Standard Model (BSM). In the first part of the talk I will present an overview of the physics reach of various searches and I will discuss the complementarity of different EDM probes. In the second part of the talk I will discuss ongoing work towards the computation of the BSM-induced neutron and proton EDM using lattice Quantum ChromoDynamics.

  399. High-Energy Physics & RIKEN Theory Seminar

    "Ab initio calculation of the neutron-proton mass difference"

    Presented by Antonin Portelli, University of Southampton, UK

    Wednesday, February 4, 2015, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  400. RIKEN/BNL Lunch Time Talk

    "Novel phase structure for lattice flavored chemical potential"

    Presented by Tatsuhiro Musumi, Brookhaven National Laboratory

    Thursday, September 6, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  401. RIKEN/BNL Lunch Time Talk

    "Heavy quark production in pA collision with rcBK evolution"

    Presented by Kazuhiro Watanabe, University of Tokyo

    Thursday, August 30, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Koji Kashiwa

  402. Nuclear Physics & RIKEN Theory Seminar

    "Constraining the nuclear equation of state by neutron star observables"

    Presented by Thomas Hell, Munich Technical University

    Friday, August 24, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

  403. RIKEN/BNL Lunch Time Talk

    "Neutron Stars and Functional Renormalization Group"

    Presented by Matthias Drews, Technical University Munich

    Thursday, August 23, 2012, 1 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  404. RIKEN/BNL Lunch Time Talk

    "Transport phenomena in NJL-type models"

    Presented by Robert Lang, Technical University Munich

    Thursday, August 23, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  405. RIKEN/BNL Lunch Time Talk

    "The Higgs boson mass -- what does it mean for the Standard Model?"

    Presented by Fedor Bezrukov, University of Connecticut/RBRC

    Thursday, August 16, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

    The Higgs boson with the mass recently announced by the LHC experiments corresponds within current precision to the boundary value between the situations when the electroweak vacuum is stable and metastable. I will discuss the latest developments in the calculation of this boundary mass and importance of measurement of other SM parameters (top quark mass and the strong coupling constant). I will also discuss what is the meaning of this boundary value in various minimal modifications of the Standard Model.

  406. RIKEN/BNL Lunch Time Talk

    "Hard Probes of QGP in strong magnetic field"

    Presented by Kirill Tuchin, Iowa State University

    Thursday, August 2, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  407. Nuclear Physics & RIKEN Theory Seminar

    "The azimuthal anisotropy of high P_t hadrons in RHIC and LHC"

    Presented by Xilin Zhang, Indiana University

    Friday, July 27, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    In this talk, I will present our study on the azimuthal anisotropy of high p_t particles (from jets) in the relativistic heavy ion collisions, which encode the information about jet energy loss in the medium as well as the medium itself. We focus on three different models with distinctive path-length and matter-density dependence of the energy loss: L^{2}, L^{3}, and near-Tc-enhancement (NTcE). We will first show our simple estimate of jet response to the shape fluctuation of the medium (initial state fluctuation) in the central 200 AGeV Au-Au collision. Second, the MC Glauber model is applied to study different Fourier-harmonics (V_{1,2,3,,,6}) of the final high P_t hadron spectrum in the non-central collisions at both RHIC and LHC (Pb-Pb collision). We find both L^{3} and NTcE can explain V_2 at RHIC (L^{2} underestimates it by roughly 20%), while L^{2} and NTcE are successful at LHC@2.76 TeV (L^{3} overestimates it by roughly 20%). In addition, we see the consistency between our NTcE calculations for other higher harmonics and the LHC@2.76 TeV data. The predictions of these harmonics for LHC@5.5 TeV will also be presented.

  408. RIKEN/BNL Lunch Time Talk

    "The QCD Plasma Near Tc: An Update"

    Presented by Jinfeng Liao, Indiana University

    Thursday, July 26, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Koji Kashiwa

  409. Nuclear Physics & RIKEN Theory Seminar

    "Hydrodynamics at large baryon densities: Understanding proton vs. anti-proton $v_2$ and other puzzles"

    Presented by Jan Steinheimer-Froschauer, University of Frankfurt/Lawrence Berkeley National Laboratory

    Friday, July 20, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Adam Bzdak

    Using hydrodynamics we explore the effects of the initial state, baryon stopping and baryon number transport on various observables such as spectra, elliptic flow and particle yields for heavy ion collisions at beam energies from $\sqrt{s_{NN}}=7.7$ to $200$ GeV. In our setup the transition from the equilibrated hydrodynamical phase to the final transport phase occurs over a broad range of temperatures/densities. Even though particle yields, extracted at this transition, can be described well by a single temperature freeze out we observe a correlation of particle mass, average transition temperature and flow velocity which allows us to successfully describe the measured non-monotonic behavior of the effective slope parameter as a function of particle mass. Furthermore we show that observed phenomena such as the centrality dependent freeze out parameters as well the asymmetry in particle/antiparticle $v_2$ at large baryon densities can be explained by a collective hydrodynamic expansion, once baryon stopping and baryon number conservation are properly taken into account. We will further discuss how the various stages of the collision contribute to the $p_{\bot}$ spectra and the mass dependence of $T_{eff}$.

  410. Nuclear Physics & RIKEN Theory Seminar

    "More on the string inspired solution to the sign problem and overlapping problem"

    Presented by Masanori Hanada, KEK Theory Center

    Friday, July 13, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    The effect of the complex phase of the fermion determinant is a key question related to the sign problem in finite-density QCD. Recently, based on a field-theoretic argument inspired by the string theory, it has been shown that ignoring the complex phase -- the phase quenching -- does not change the expectation values of a class of observables in a certain region of the phase diagram when a number of colors Nc is large. In this talk we briefly explain this equivalence and show that the same equivalence holds in effective models and holographic models. We show, in a unified manner, that the phase quenching gives exact results for a class of fermionic observables (e.g., chiral condensate) in the mean-field approximation and for gauge-invariant gluonic observables (e.g., Polyakov loop) up to one-meson-loop corrections beyond mean field. We also discuss implications for the lattice simulations and confirm good quantitative agreement between our prediction and existing lattice QCD results. Therefore the phase quenching provides rather accurate answer already at Nc=3 with small 1/Nc corrections which can be taken into account by the phase reweighting.

  411. RIKEN/BNL Lunch Time Talk

    "Evolution of singularities in unequal time correlator in thermalization of strongly coupled gauge theory"

    Presented by Shu Lin, RBRC

    Thursday, July 12, 2012, 12:30 pm
    Building, 510/Room 2-160

    Hosted by: Tomomi Ishikawa

    Thermalization of strongly coupled gauge theory can be described by a gravitational collapse process via gauge/gravity duality. We studied the evolution of unequal time correlator in a gravitational collapse background, which allowed us to probe different stages of thermalization process. We found that the singularities of the correlator are consistent with geometric optics picture in the gravitational collapse background. We found the thermalization is characterized by the disappearance of singularities on real time axis and possible emergence of singularities in complex time plane in the correlator.

  412. Nuclear Physics & RIKEN Theory Seminar

    "Quark superfluidity in the two-fluid formalism"

    Presented by Andreas Schmitt, Vienna Technical University

    Friday, June 29, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    Various observables of neutron stars depend on hydrodynamic properties of the matter inside the star. This matter is likely to be a superfluid, for instance in the color-flavor locked (CFL) phase of quark matter. I will discuss the nontrivial superfluid properties of CFL and, in particular, present a "translation" between microscopic, field-theoretical calculations and the two-fluid picture of a relativistic superfluid.

  413. Nuclear Physics & RIKEN Theory Seminar

    "Putting a Saturation Spin on Transverse Spin Asymmetries"

    Presented by Matt Sievert, Ohio State University

    Friday, June 22, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    In hadron collisions, the single transverse spin asymmetry (STSA) is an observable describing the left-right asymmetry in the spectrum of produced particles when one of the colliding hadrons is polarized transverse to the beam axis. Since the discovery of unexpectedly large STSA's at the Tevatron in the 1990's, these spin asymmetries have consistently challenged accepted paradigms in factorization, universality, and perturbative QCD. Current theoretical treatments describe the generation of asymmetry in two nonperturbative sectors: the intrinsic parton distribution functions (Sivers effect) and the fragmentation functions (Collins effect). In this talk, I will discuss how the systematic enhancement of certain scattering processes for high energies or large nuclei (saturation formalism) leads to an asymmetry that can be generated at the perturbative level. Our new mechanism generates the STSA through a C-odd scattering process known as the “odderon,” a hypothetical interaction originating from the field of Regge physics. I will present our general result deriving the new mechanism and some numerical estimates illustrating its features. I will conclude by describing some of the scaling properties of our mechanism and illustrating its essential features.

  414. RIKEN/BNL Lunch Time Talk

    "Critical endpoint for deconfinement in matrix and other effective models"

    Presented by Koji kashiwa, RBRC

    Thursday, June 21, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  415. High-Energy Physics & RIKEN Theory Seminar

    "Lattice QCD and Flavor Physics"

    Presented by Jack Laiho, University of Glasgow

    Wednesday, June 13, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Amarjit Soni

  416. RIKEN/BNL Lunch Time Talk

    "Nucleon structure from 2+1-flavor dynamical DWF QCD at nearly physical pion mass"

    Presented by Shigemi Ohta, KEK/RBRC

    Thursday, June 7, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

    I report the current status of joint RBC+UKQCD numerical lattice QCD study of nucleon structure using several 2+1-flavor dynamical domain-wall fermions (DWF) ensembles with pion mass as low as 170 MeV and spatial volume as large as \(L=4.6\) fm across. Isovector form factors of vector and axialvector currents and some low moments of isovector structure functions will be discussed. In particular the results for the ratio of vector and axial charges, gA/gV, calculated at pion mass of about \(m_\pi=250\) MeV seems to confirm our earlier conjecture that the quantity scales with a parameter \(m_\pi L\).

  417. High-Energy Physics & RIKEN Theory Seminar

    "High Q^2 physics from lattice QCD"

    Presented by Dru Renner, Jefferson Laboratory

    Monday, June 4, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Amarjit Soni

  418. RIKEN/BNL Lunch Time Talk

    "The thermodynamics of the 2-dimensional O(N) model"

    Presented by Elina Seel, University of Frankfurt

    Thursday, May 31, 2012, 1 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  419. RIKEN/BNL Lunch Time Talk

    "Two-flavor linear sigma model in presence of axial anomaly from Functional Renormalization Group"

    Presented by Mara Grahl, University of Frankfurt

    Thursday, May 31, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  420. Nuclear Physics & RIKEN Theory Seminar

    "Aspects of the non-equilibrium dynamics of relativistic heavy ion collisions"

    Presented by Soeren Schlichting, University of Heidelberg

    Friday, May 25, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    The non-equilbrium dynamics of relativistic heavy ion collisions provides one of the key challenges in our current understanding of the experiments carried out at RHIC and the LHC. In this talk I will discuss the evolution of the 'Glasma' created immediately after the collision of heavy nuclei. I will discuss the different dynamical stages which arise in this context and are characterized by the rapid growth of quantum fluctuations due to non-equilbirum instabilities, the onset of non-linear effects and ultimately the approach to thermal equilibrium. Both numerical and analytical considerations will be presented.

  421. RIKEN Lunch Seminar

    "The transition temperature in QCD"

    Presented by Alexei Bazavov, Brookhaven National Laboratory

    Thursday, May 24, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  422. RIKEN/BNL Lunch Time Talk

    "Flavors in dynamical electroweak symmetry breaking"

    Presented by Kimmo Tuominen, University of Jyvaskyla & Helsinki

    Thursday, May 10, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  423. Nuclear Physics & RIKEN Theory Seminar

    "TBA"

    Presented by Ian Balitsky, Old Dominion Univ./Jlab

    Friday, May 4, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

  424. RIKEN/BNL Lunch Time Talk

    "Electroweak Axions, Instantons and the Cosmological Constant"

    Presented by Larry McLerran, Brookhaven National Laboratory

    Thursday, May 3, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

    I argue that in electroweak theory, an electroweak axion has the right energy density to correspond to the dark energy. This electroweak axion is the Goldstone boson of B+L symmetry, in the absence of instantons. Instantons generate an axion mass. The resulting axion has a mass of the order the inverse size of the universe. The dark energy is associated with the axion field energy. This result assumes no new physics up to of order the Planck scale.

  425. Nuclear Physics & RIKEN Theory Seminar

    "Scattering from N=4 to N=0"

    Presented by Simon Caron-Huot, IAS Princeton

    Friday, April 27, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    I will discuss the simplicity found empirically for gluon scattering amplitudes in planar N=4 super Yang-Mills over the past few years, and argue that its origin is now fully understood. The amplitudes are governed by symmetries, and can be computed using them. I will then discuss how this leads to striking facts about individual Feynman integrals, which remain true beyond N=4 and can be applied to QCD.

  426. RIKEN/BNL Lunch Time Talk

    "Chiral symmetry breaking in lattice QED model with fermion brane"

    Presented by Eigo Shintani, RBRC

    Thursday, April 26, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  427. High-Energy Physics & RIKEN Theory Seminar

    "Precise constraints on CP violation from lattice QCD"

    Presented by Christoph Lehner, RBRC

    Wednesday, April 25, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Amarjit Soni

  428. Joint HET/RIKEN/YITP Seminar

    "A novel phase in SU(3) gauge theory with many light fermions"

    Presented by Anna Hasenfratz, University of Colorado at Boulder

    Wednesday, April 18, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christoph Lehner

    In this talk I will discuss the results of our recent study of the phase structure of SU(3) lattice gauge theory with $N_f = 12$ and 8 staggered fermions in the fundamental representation. For small fermion masses we found two bulk phase transitions at strong gauge couplings. The phase between the two transitions appears to be a novel phase that breaks the single site shift symmetry of staggered fermions. The eigenvalue spectrum of the Dirac operator, the static potential and the meson spectrum collectively establish that this novel phase is confining but chirally symmetric. The phase is bordered by first-order phase transitions, and since we find the same phase structure with $N_f = 8$ fermions, it is most likely that this novel phase is a strong-coupling lattice artifact, the existence of which does not imply IR conformality. (ArXiv:1111:2317)

  429. Nuclear Physics & RIKEN Theory Seminar

    "Understanding the noise in lattice calculations"

    Presented by Amy Nicholson, University of Maryland

    Friday, April 13, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    Learning about the QCD phase diagram at low temperatures using lattice QCD has proven highly difficult due to the well-known sign problem, which manifests itself as a noise problem in canonical formalisms. In this talk, I will show that noise in lattice calculations tends to fall into two classes, corresponding to symmetric and long-tailed distributions, respectively, based on the physics of the system under study. I will present a lattice study of unitary fermions, a simplified system which we can use to understand the noise problem for long-tailed distributions, and show that understanding the distribution allows us to both tame the noise problem and extract previously unknown physical results for systems of bosons at unitarity, known as Efimov states, from the distribution itself. Finally, I will discuss the possible applicability of these findings to lattice QCD calculations.

  430. Nuclear Physics & RIKEN Theory Seminar

    "Recent results from chiral effective models"

    Presented by Dirk Rischke, J.W. Goethe University, Frankfurt, Germany

    Friday, April 6, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    In this talk, I present results from an effective model based on the linear representation of the chiral U(N_f)_r x U(N_f)_l symmetry of QCD. It is demonstrated that a reasonable fit of the mass parameters and coupling constants of the model to hadron vacuum properties is possible. This fit can contribute to answering the question about the quark content of the scalar isoscalar mesons. The ultimate goal is to use this model to investigate signatures for chiral symmetry restoration at nonzero temperatures and densities.

  431. Nuclear Physics & RIKEN Theory Seminar

    "To be announced"

    Presented by Dirk Rischke, J. W. Goethe University, Frankfurt, Germany

    Friday, April 6, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Robert Pisarski

  432. RIKEN/BNL Lunch Time Talk

    "A saga of the weak and the strong: hadronic parity violation"

    Presented by Brian Tiburzi, City College of New York and RBRC

    Thursday, April 5, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Tomomi Ishikawa

  433. High-Energy Physics & RIKEN Theory Seminar

    "Parity violation constraints on top physics"

    Presented by Sean Tulin, Michigan Center for Theoretical Physics

    Wednesday, April 4, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Elisabetta Furlan

    An excess top forward-backward asymmetry has been measured by the CDF and D0 collaborations, motivating many new physics theories beyond the Standard Model and searches for top-related anomalies at the LHC. I discuss the implications of low-energy precision tests of parity violation (PV) on these new physics models, and in fact many of the most promising scenarios are actually ruled out by current PV constraints.

  434. RIKEN Lunch Seminar

    "Holographic Fermi surfaces"

    Presented by David Vegh, Stony Brook University

    Thursday, March 29, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  435. High-Energy Physics & RIKEN Theory Seminar

    "Probing Nonstandard Standard Model Backgrounds with LHC Monojets"

    Presented by Michael Graesser, LANL

    Tuesday, March 27, 2012, 11 am
    Building 510 / Room 2-95

    Hosted by: Elisabetta Furlan

  436. Nuclear Physics & RIKEN Theory Seminar

    "Heavy Flavor in Hot/Dense Matter"

    Presented by Ralf Rapp, Texas A&M

    Friday, March 23, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    Heavy quarks (charm and bottom) provide a versatile tool to study properties of the Quark-Gluon Plasma (QGP) and their manifestation in ultrarelativistic heavy-ion collisions. The large quark mass offers unique opportunities for theoretical control over basic in-medium quantities. We will discuss how a potential-based T-matrix approach can be used to comprehensively evaluate both quarkonium bound-state properties and heavy-flavor transport in the medium. Constraints from vacuum spectroscopy, perturbative QCD and thermal lattice-QCD are applied to enhance the reliability of the calculations. The heavy-light quark T-matrices in the QGP lead to resonance formation close to Tc which naturally lead to coalescence mechanisms for hadronization. Pertinent Langevin simulations of heavy-flavor transport through QGP, hadronization and the hadronic phase are implemented into a hydrodynamic evolution to arrive at a uniform strong-coupling treatment of both micro- and macro-physics in heavy-flavor observables.

  437. Nuclear Physics & RIKEN Theory Seminar

    "Di-hadron angular correlations in Color Glass Condensate formalism: multi-gluon correlators"

    Presented by Jamal Jalilian-Marian, Baruch College

    Friday, March 16, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    Di-hadron angular correlations in the forward rapidity region of proton-nucleus collisions probe multi-gluon correlators (n-point functions of Wilson lines) in the wave function of target nucleus at small x and thus, provide a more detailed picture of QCD dynamics at high energy (CGC). The Renormalization Group equations that govern the energy dependence of these n-point functions will be derived and their approximate solutions motivated. A connection to an alternative approach to high energy QCD, based on BJKP equation involving pomeron and Reggeon exchanges, will be made.

  438. RIKEN/BNL Lunch Time Talk

    "The Spin of Holographic Electrons at Nonzero Temperature and Density"

    Presented by Christopher Herzog, YITP of Stony Brook

    Thursday, March 15, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  439. Nuclear Physics & RIKEN Theory Seminar

    "Thermal production of relativistic right-handed neutrinos"

    Presented by Dietrich Bodeker, Universitaet Bielefeld

    Wednesday, March 14, 2012, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern P. Schenke

    The production of right-handed neutrinos is important for models of baryogenesis through leptogenesis. Relativistic right-handed neutrinos are produced through 2 -> 2 scattering and nearly collinear 1 <-> 2 emission which involves multiple scattering mediated by soft gauge bosons. I discuss the complete leading order calculation of the production rate.

  440. RIKEN/BNL Lunch Time Talk

    "Baryon number probability distribution near a phase transition"

    Presented by Kenji Morita, YITP, Kyoto University

    Thursday, March 8, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

    I discuss the baryon number probability distribution at finite temperature and chemical potential. Starting from a model thermodynamic potential which has divergent kurtosis at the phase transition, I show how to calculate the probability distribution and its relation to the analytic structure of the thermodynamic potential at complex chemical potential.

  441. High-Energy Physics & RIKEN Theory Seminar

    "Constraining Dark Matter"

    Presented by Haibo Yu, University of Michigan

    Wednesday, March 7, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Yingchuan Li

    Astrophysical and cosmological observations provide compelling evidence for the existence of dark matter in the universe, but its particle physics nature remains mysterious. In this talk, I will discuss how hardron colliders and neutron stars can help us understand dark matter properties. Using an effective field theory approach, we show that mono-jet+missing energy searches at the Tevatron and LHC can provide a probe of dark matter, which is complementary to direct detection experiments, and in some cases the colliders provide an even stronger constraint. Stellar systems are natural laboratories for exploring dark matter. We show dark matter particles accumulated in old neutron stars can form mini black holes and lead to the destruction of host stars. The observation of old neutron stars actually excludes a class of dark matter models.

  442. Nuclear Physics & RIKEN Theory Seminar

    "Hydrodynamic Fluctuations in Relativistic Heavy Ion Collisions"

    Presented by Berndt Mueller, Duke University

    Friday, March 2, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    The success of relativistic hydrodynamics in describing the fireball created in ultrarelativistic heavy ion collisions opened the possibility to study the properties of strongly interacting matter at extremely high temperatures and densities near thermal equilibrium. A remarkably small value of the shear viscosity near the unitary limit has been deduced from comparison of the results of relativistic viscous fluid dynamics simulations with data from Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Due to the fluctuation-dissipation theorem, the shear and bulk viscosities not only control the dissipative properties of a fluid in the limit of small velocity gradients, but they also control the magnitude of hydrodynamic fluctuations in the fluid. In my talk, I will explain the relativistic theory of hydrodynamical fluctuations in general and show how it can be applied to the evolution of the quark-gluon plasma formed in relativistic heavy-ion collisions. As an example, I will present the semi-analytic solution of the equations of hydrodynamic fluctuations around the boost invariant Bjorken flow and discuss the structure of the correlation function of particle multiplicity correlations in rapidity space.

  443. RIKEN/BNL Lunch Time Talk

    "KNO scaling of fluctuations in pp and pA, and higher-order eccentricities in heavy-ion collisions"

    Presented by Adrian Dumitru, CUNY & RBRC

    Thursday, March 1, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  444. Nuclear Physics & RIKEN Theory Seminar

    "Deeply Virtual Compton Scattering at a proposed high-luminosity Electron-Ion-Collider"

    Presented by Dieter Mueller, Brookhaven National Laboratory

    Friday, February 24, 2012, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    We study deeply virtual Compton scattering at a proposed electron-ion-collider and explore the possible impact of such measurements for the access of generalized parton distributions. In particular we give emphasize to the transverse distribution of sea quarks and gluons and show that such measurements will also provide information on the angular momentum sum rule.

  445. RIKEN/BNL Lunch Time Talk

    "Jet Fragmentation From Two Dimensional Field Theory"

    Presented by Frasher Loshaj, Stony Brook University

    Thursday, February 23, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

    We consider QED_2 (Schwinger Model) as a toy model for studying jet fragmentation in both vacuum and medium. Using the bosonized version of the model, we calculate the fragmentation function of jets in e^+e^- annihilation and find reasonable agreement with the data. We then apply the model to jet quenching in heavy ion collisions, and address the jet fragmentation scaling observed recently at the LHC.

  446. Joint HET/RIKEN Seminar

    "Lattice vs. Technicolor"

    Presented by Tom DeGrand, University of Colorado at Boulder

    Wednesday, February 22, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christoph Lehner

  447. High-Energy Physics & RIKEN Theory Seminar

    ""Lattice vs. Technicolor""

    Presented by Thomas DeGrand, University of Colorado at Boulder

    Wednesday, February 22, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christoph Lehner

  448. RIKEN/BNL Lunch Time Talk

    "Direct photon physics in heavy ion collisions ~Current status and Future~"

    Presented by Takao Sakaguchi, Brookhaven National Laboratory

    Thursday, February 9, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

    Direct photons are a promising probe to directly explore the partonic system which are not possible by hadronic probes that are often distorted in the hadronization process. The PHENIX experiments at RHIC measured high pT photons coming from initial hard scattering process in heavy ion collisions for the first time and published in 2005. Then, recently, the experiment came up with low pT photon results, supposedly coming from the hot partonic matter. These measurements characterized the initial state and partonic matter state, but there are states after the collisions yet to be investigated. I will present on the recent results on direct photons from the PHENIX experiments, and then discuss what we can explore with direct photon measurement in the future RHIC runs.

  449. High-Energy Physics & RIKEN Theory Seminar

    "The Charge Radius of the Proton, a Five Sigma Discrepancy?"

    Presented by Gil Paz, Wayne State University

    Wednesday, February 8, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Yingchuan Li

  450. Nuclear Physics & RIKEN Theory Seminar

    "Studying 3D structure of proton with neural networks"

    Presented by Kresimir Kumericki, University of Zagreb

    Friday, February 3, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    3-dimensional quark-gluon structure of fast proton, encoded in generalized parton distributions (GPDs), is both a testing ground for QCD and an important input into analysis of proton-proton collisions, such as those at LHC. However, extraction of GPDs from experimental data is fraught with uncertainties. After describing the neural network method of data analysis, it will be shown how this method enables elegant and reliable estimation of relevant structure functions. This will be applied to extraction of GPD H from HERMES data on Deeply Virtual Compton Scattering (DVCS).

  451. RIKEN/BNL Lunch Time Talk

    "Instantons and sphalerons in magnetic field"

    Presented by Grockce Basar, Stony Brook University

    Thursday, February 2, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

    We study the properties of the Euclidean Dirac equation for a light fermion in the presence of both a constant abelian magnetic field and an SU(2) instanton. In particular, we analyze the zero modes analytically in various limits, both on R^4 and on the four-torus, in order to compare with recent lattice QCD results, and study the implications for the electric dipole moment. We also present a holographic computation of the sphaleron rate in a medium with constant magnetic flux. We show that in the strong field limit, the rate has a linear dependence in B.

  452. High-Energy Physics & RIKEN Theory Seminar

    "The Little Hierarchy Problem in a Generalized NMSSM"

    Presented by Christopher Kolda, University of Notre Dame

    Wednesday, February 1, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Elisabetta Furlan

  453. Nuclear Physics & RIKEN Theory Seminar

    "Mass-Gaps, Gluon mass-terms and Supersymmetry in D=2+1"

    Presented by Abhishek Agarwal, American Physical Society

    Friday, January 20, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    In this talk - based on work in collaboration with V.P.Nair and A. Fayyazuddin - I'll focus on the mechanism of the dynamical generation of mass-gaps in the spectrum of three dimensional gauge theories in a gauge invariant formalism; originally due to Kim, Karabali and Nair. I will be particularly interested in addressing the interplay between dynamical mass-gaps and supersymmetry and present a first principles explanation for the absence of mass-gaps for N >2 SUSY for Yang-Mills theories [without additional hypermultiplets] in D=3. I will also discuss the compatibility of mass-gap with minimal supersymmetry and discuss how these results square with many expectations based on other non-perturbative approaches. Finally I will try to comment on a possible generalization of the mechanism of dynamical mass-generation to a manifestly Lorentz invariant framework.

  454. HET/RIKEN Lunch Seminar

    "More on lattice chiral symmetry and minimal doubling"

    Presented by Mike Creutz, Brookhaven National Laboratory

    Friday, January 20, 2012, 12 pm
    Building 510 / Room 2-160

    Hosted by: Amarjit Soni

  455. Joint HET/RIKEN Seminar

    "Nonperturbative QCD vacuum polarization corrections"

    Presented by Dru Renner, Jefferson Laboratory

    Wednesday, January 18, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christoph Lehner

  456. Nuclear Physics & RIKEN Theory Seminar

    "Correlations from charge conservation -- Determining fundamental properties of the QGP"

    Presented by Scott Pratt, Michigan State University

    Friday, January 13, 2012, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    Charge correlations from lattice QCD provide insight into the degrees of freedom of the quark-gluon plasma. Charge correlations can also be measured experimentally at RHIC and at the LHC. However, comparing the two has seemed problematic since lattice calculations assume a particle bath while charge is locally conserved in a collision. The situation is further complicated by the dynamics of hadronization. I will show how one can account for effects of local charge conservation and pierce the fog of hadronization to make predictions for experimental correlations that are sensitive to the corresponding quantities measured on the lattice.

  457. RIKEN/BNL Lunch Time Talk

    "Ions in biology: Water and Proteins"

    Presented by Purushottam Dixit, Brookhaven National Laboratory

    Thursday, January 12, 2012, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

    The milieu of all biological activity is a complex electrolyte solution wherein inorganic ions play an important role. Classical electrolyte theory explains some of the activity of ionic species yet more interesting phenomena in biology such as the electrical activity of the heart and firing of neurons rely on the specific chemistry of the ions. We need a statistical mechanical theory to separately understand the role of physics and chemistry in the interaction of ions with biomaterials. The excess free energy of ion hydration/binding contains all the information about the behavior of a given ion in solution. We develop a physically motivated framework to interrogate the different contributors to the excess free energy of an ion. We then apply the framework to the study of Na+(aq). We present a possible explanation for the disparate reports of experimentally determined coordination numbers for Na+(aq). We then apply the same framework and provide an explanation for the long standing puzzle of K+ over Na+ selectivity of the KcsA K+ channel, a membrane protein that excludes the smaller Na+ from the ionic current across neurons while allowing the larger K+ to pass.

  458. Nuclear Physics & RIKEN Theory Seminar

    "Multiplicities from black-hole formation in heavy-ion collisions"

    Presented by Anastasios Taliotis, University of Crete

    Friday, December 16, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    The formation of trapped surfaces in the head-on collision of shock waves in conformal and non-conformal backgrounds is investigated. The backgrounds include all interesting conning and non-conning backgrounds that may be relevant for QCD. Several transverse proles of the shocks are investigated including distributions that fall-o as powers or exponentials. Dierent ways of cutting-o the UV contributions (that are expected to be perturbative in QCD) are explored. Under some plausible simplifying assumptions our estimates are converted into predictions for multiplicities for heavy-ion collisions at RHIC and LHC.

  459. Nuclear Physics & RIKEN Theory Seminar

    "Thermalization in collisions of extremely large nuclei at extremely large energies"

    Presented by Aleksi Kurkela, McGill University

    Friday, December 9, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    Hydrodynamical analysis of experimental data of ultra relativistic heavy ion collisions seems to indicate that the hot QCD matter created in the collisions thermalizes very quickly. Theoretically, we have no idea why this should be true. In my talk, I will describe how the thermalization takes place in the most theoretically clean limit -- that of large nuclei at asymptotically high energy per nucleon, where the system is described by weak-coupling QCD. In this limit, plasma instabilities dominate the dynamics from immediately after the collision until well after the plasma becomes nearly in equilibrium at time Qt ~ alpha^(-5/2).

  460. RIKEN/BNL Lunch Time Talk

    "Understanding the heavy quarkonia production at hadron colliders within NRQCD factorization"

    Presented by Yan-Qing Ma, Brookhaven National Laboratory

    Thursday, December 8, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  461. Nuclear Physics & RIKEN Theory Seminar

    "Recent progress in EFTs for Quarkonium at finite temperature"

    Presented by Jacopo Ghiglieri, McGill University, Montreal, Canada.

    Thursday, December 8, 2011, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    In this talk I will introduce non-relativistic EFTs of QCD for heavy quarkonium and their generalization to finite temperatures that has been brought forward recently. I will show how this framework allows a systematic treatment of the many scales characterizing the system. I will concentrate on the realization of this framework that is more related to the phenomenology of the Upsilon(1S) and I will show recent developments in the comparison of the widths obtained in this framework with those in the literature.

  462. Joint HET/RIKEN/YITP Seminar

    "Hybrid Monte Carlo simulation of graphene"

    Presented by Claudio Rebbi, Boston University

    Wednesday, December 7, 2011, 2 pm
    Building 510 / Room 2-84

    Hosted by: Christoph Lehner

    I will briefly review the Hamiltonian of the graphene system and show how the partition function and Green's functions for the quadratic Hamiltonian can be expressed in path integral form by using fermion coherent states. I will then show how one can incorporate the Coulomb interaction into the path integral and how this can be simulated with the hybrid Monte Carlo technique. I will present then early results for the Green's functions obtained with this method. (Based on research done in collaboration with Richard Brower and David Schaich.)

  463. Nuclear Physics & RIKEN Theory Seminar

    "QCD phase diagram: universality and continuity"

    Presented by Naoki Yamamoto, University of Washington

    Friday, December 2, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    We discuss the phase diagrams of QCD and QCD-like theories from the viewpoint of the large-Nc universality and the quark-hadron continuity. We first show that the whole or the part of the phase diagrams are universal between QCD and QCD-like theories based on the exact large-Nc equivalence. We then see that all the QCD-like theories and QCD with three-flavor and three-color exhibit a quark-hadron continuity at low temperature and finite density. From our universality and QCD inequalities, we derive some rigorous results on the chiral phase transition at large Nc. We also comment on the implications of our results for the recent (and future) lattice QCD simulations.

  464. RIKEN/BNL Lunch Time Talk

    "Anomaly-induced charges in nucleons"

    Presented by Yu Maezawa, Brookhaven National Laboratory

    Thursday, December 1, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  465. RIKEN/BNL Lunch Time Talk

    "Factorization with transverse momentum dependent parton distribution functions"

    Presented by Ted Rogers, Stony Brook University

    Thursday, November 17, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  466. RIKEN/BNL Lunch Time Talk

    "Exploring dynamical QED effects with the reweighting method"

    Presented by Tomomi Ishikawa, RBRC

    Thursday, November 10, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  467. High-Energy Physics & RIKEN Theory Seminar

    "Flavour Symmetric Sectors and Collider Physics"

    Presented by Michael Trott, Perimeter Institute for Theoretical Physics

    Wednesday, November 9, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Yingchuan Li

    We discuss the phenomenology of effective field theories with new scalar or vector representations of the Standard Model quark flavor symmetry group, allowing for large (aligned) flavor breaking involving the third generation. Such field content can have a relatively low mass scale ≤TeV and O(1) couplings to quarks, while being consistent with both flavor violating and flavor diagonal constraints. These theories therefore have the potential for early discovery at LHC, and provide a flavor safe "tool box" for addressing anomalies at colliders and low energy experiments. We catalogue the possible flavor symmetric representations, and consider applications to the anomalous Tevatron t-tbar forward backward asymmetry and Bs mixing measurements. More general collider signatures and constraints on flavor symmetric models are also discussed.

  468. HET/RIKEN Lunch Seminar

    "Conformal Fixed Point of SU(3) Gauge Theory with 12 Fundamental Fermions in the Twisted Polyakov Loop Scheme"

    Presented by Eigo Shintani, RBRC

    Friday, November 4, 2011, 12 pm
    Building 510 / Room 2-160

    Hosted by: Amarjit Soni

  469. RIKEN/BNL Lunch Time Talk

    "Probing QCD phase diagram with charge fluctuations"

    Presented by Vladimir Skokov, Brookhaven National Laboratory

    Thursday, November 3, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  470. High-Energy Physics & RIKEN Theory Seminar

    "Dark Matter from Minimal Flavor Violation"

    Presented by Brian Batell, University of Chicago

    Wednesday, November 2, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Yingchuan Li

    We consider theories of flavored dark matter, in which the dark matter particle is part of a multiplet transforming nontrivially under the flavor group of the Standard Model in a manner consistent with the principle of Minimal Flavor Violation (MFV). MFV automatically leads to the stability of the lightest state for a large number of flavor multiplets. If neutral, this particle is an excellent dark matter candidate. Furthermore, MFV implies specific patterns of mass splittings among the flavors of dark matter and governs the structure of the couplings between dark matter and ordinary particles, leading to a rich and predictive cosmology and phenomenology. We present an illustrative phenomenological study of an effective theory of a flavor SU(3)_Q triplet, gauge singlet scalar.

  471. RIKEN/BNL Lunch Time Talk

    "Calculating the incoherent and total cross-sections in exclusive diffractive vector meson production in eA"

    Presented by Tobias Toll, Brookhaven National Laboratory

    Thursday, October 27, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  472. High-Energy Physics & RIKEN Theory Seminar

    "Standard Model Prediction of Epsilon_k at NNLO"

    Presented by Joachim Brod, University of Cincinnati

    Wednesday, October 26, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Yingchuan Li

    Neutral Kaon mixing plays an important role in the phenomenology of the standard model and its extensions because of its sensitivity to high-energy scales. In particular epsilon_K, parameterising indirect CP violation, serves as an important constraint on models of new physics, in this way complementing the direct searches at LHC. In order to exploit this sensitivity, a precise standard-model prediction is crucial. In this seminar I will give a summary of the standard-model prediction of epsilon_K and the Kaon mass difference Delta M_K, and present our recent NNLO QCD calculation of the contributions eta_ct and eta_cc to the Delta S = 2 effective Hamiltonian. It turns out that the NNLO corrections are very large, and I will discuss the impact on epsilon_K and the theory uncertainties in some detail.

  473. Nuclear Physics & RIKEN Theory Seminar

    "Solving the Boltzmann Equation for Relativistic Systems"

    Presented by Miller Mendoza Jimenez, ETH, Zurich

    Friday, October 14, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    Two Lattice Boltzmann (LB) formulations to solve the relativistic Boltzmann equation are pre- sented. The first method is numerically validated and applied to the propagation of shock-wave in quark-gluon plasmas and the impact of a supernova blast-wave on massive interstellar clouds. The simulations of shock waves are performed in the low and high viscosities regime, using three different computational models, the relativistic lattice Boltzmann (RLB), the Boltzmann Approach Multi- Parton Scattering (BAMPS), and the viscous sharp and smooth transport algorithm (vSHASTA). From the comparison of the results, we conclude that the RLB model departs from BAMPS in the case of high speeds and high temperature (viscosities), the departure being due to the fact that the RLB is based on a quadratic approximation of the Maxwell-Ju ̈ttner distribution, which is only valid for sufficiently low temperature and velocity. Finally, the second method, which is a fully relativistic version of the previous one, is briefly described showing that is capable to handle general geometries and ultrarelativistic cases.

  474. RIKEN Lunch Seminar

    "Symmetric forward-backward correlations as seen at RHIC"

    Presented by Adam Bzdak, RBRC

    Thursday, October 13, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  475. Nuclear Physics & RIKEN Theory Seminar

    "Histogram method for the calculation of QCD equation of state at finite density"

    Presented by Shinji Ejiri, Niigata University

    Friday, October 7, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Frithjof Karsch

    We propose a new approach to finite density lattice QCD based on a histogram method and discuss the QCD phase structure at high temperature and density. Because the quark determinant is complex at finite density, the Monte-Carlo method cannot be applied directly. We use a reweighting method and try to solve the problems which arise in the reweighting method, i.e. the sign problem and the overlap problem. We discuss the quark mass and chemical potential dependence of the probability distribution function and examine the applicability of the approach.

  476. Joint HET/RIKEN/YITP Seminar

    "Searching for (Nearly) Conformal Dynamics on the Lattice"

    Presented by Ethan T. Neil, Fermilab

    Wednesday, October 5, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christoph Lehner

  477. Nuclear Physics & RIKEN Theory Seminar

    "New results on "jet" stopping in AdS/CFT"

    Presented by Peter Arnold, University of Virginia

    Friday, September 30, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    At weak coupling, the stopping distance of high-energy partons in QCD and QCD-like plasmas scales with energy as E^(1/2). One may investigate a similar question at strong coupling in QCD-like theories with gravity duals, such as N=4 SUSY Yang-Mills. Various authors have found that the maximum stopping distances in such strongly-coupled theories scales instead as E^(1/3). I will report on work with Diana Vaman showing that there is an important distinction between typical and maximum stopping distances, and the typical stopping distance scales with yet a different power law. I will also try to give some context contrasting different theoretical approaches to using AdS/CFT to study jet stopping and give my take on what, if anything, we learn about the theory of jet stopping from such investigations.

  478. RIKEN Lunch Seminar

    "Interaction of non-Abelian vortices with quasiparticles in high density QCD"

    Presented by Yuji Hirono, University of Tokyo

    Thursday, September 29, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  479. RIKEN Lunch Seminar

    "Exploring real-time functions on the lattice with inverse propagator and self-energy"

    Presented by Prof. Masakiyo Kitazawa, Osaka University

    Thursday, September 22, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

  480. RIKEN Lunch Seminar

    "Transverse Spin and Transverse Structure of the Nucleon"

    Presented by Jian-ping Chen, Jefferson Laboratory

    Thursday, September 15, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Zhongbo Kang

    Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions (PDFs) in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction (QCD). The transverse spin structure and the TMDs have been the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has been part of the exploration of this effort. With 12 GeV energy upgrade, Jefferson Lab (JLab) will provide the most precise multi-dimensional map of the TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space. Combining with the world data, the transverse spin (transversity) in the valence quark region will be extracted with a good precision and the u and d quark tensor charges of the nucleon will be determined. The precision information on TMDs will also allow a detailed study of the quark orbital motion and its correlation with the quark and the nucleon spins. The planned future Electron-Ion Collider (EIC) will greatly expand the kinematical reach to allow a precision study of the TMDs of the sea quarks and gluons, in addition to completing the study in the valence region.

  481. Nuclear Physics & RIKEN Theory Seminar

    "A holographic model for large N thermal QCD"

    Presented by Mohammed Mia, Columbia University

    Friday, September 9, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    Abstract: We summarize the dual gravity description for a thermal gauge theory, reviewing the key features of our holographic model of large N QCD and elaborating on some new results. The theory has matter in the fundamental representation and the gauge coupling runs logarithmically with energy scale at low energies. At the highest energies the theory becomes approximately scale invariant, much like what we would expect for large N QCD although not with asymptotic freedom. In this limit the theory has a gravity dual captured by an almost classical supergravity description with a controlled quantum behavior, such that by renormalizing the supergravity action, we can compute the stress tensor of the dual gauge theory. From the stress tensor we obtain the shear viscosity and the entropy of the medium at a temperature T , and the violation of the bound for the viscosity to the entropy ratio is then investigated. By considering dynamics of open strings in curved spacetime described by the supergravity limit, we compute the drag and diffusion coefficients for a heavy parton traversing the thermal medium. It is shown that both coefficients have a logarithmic dependence on momentum, consistent with pQCD expectations. Finally, we study the confinement/deconfinement mechanism for quarks by analyzing open strings in the presence of the flavor seven branes. We find linear confinement of quarks at low temperatures, while at high temperatures the quarkonium states melt, a behavior consistent with the existence of a deconfined phase.

  482. Nuclear Physics & RIKEN Theory Seminar

    "Some issues in applications of gauge/gravity duality to heavy ion collisions"

    Presented by Hong Liu, Massachusetts Institute of Technology

    Friday, August 26, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

  483. RIKEN Lunch Seminar

    "Fluctuation and Flow Probes of Early-Time Correlations"

    Presented by Sean Gavin, Wayne State University

    Thursday, August 25, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  484. High-Energy Physics & RIKEN Theory Seminar

    "Observable Scalars from Neutrino Mixing"

    Presented by Ernest Ma, UC-Riverside

    Wednesday, August 24, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Hye-Sung Lee

    If neutrino mixing comes from a non-Abelian discrete symmetry such A(4), T(7), or Delta(27), the scalars which support such a symmetry in a renormalizable theory may be observable at the Large Hadron Collider. The key is a residual Z(3) symmetry (lepton triality) in the Yukawa sector involving the charged-leptons. Scalars which decay into two different charged leptons, such as mu and tau, or tau and e, are especially important. Their observability at the LHC is discussed.

  485. Nuclear Physics & RIKEN Theory Seminar

    "Non-particle physics of QCD near the phase transition"

    Presented by Antal Jakovac, Technical University of Budapest, Budapest

    Friday, August 19, 2011, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    Treating QCD near the (would-be) phase transition temperature, the conventional perturbative approaches (eg. perturbative QCD, chiral perturbation theory) fail, because the theory becomes too strongly interacting. In parallel, the matter properties change from a gas-like plasma of the perturbative regimes to a fluid-like matter. We may still hope to maintain the small-coupling perturbative description in this regime as well, if we find the adequate degrees of freedom. In the talk I try to argue that the adequate degrees of freedom of QCD in the critical regime are excitations with broad spectral functions. Being not on-shell particles, even a non-interacting model of them can show interesting, unexpected properties. I discuss the generic consequences for transport and present model calculations for thermodynamics.

  486. RIKEN Lunch Seminar

    "Nucleon structure from 2+1-flavor dynamical DWF lattice QCD at nearly physical pion mass"

    Presented by Shigemi Ohta, RBRC

    Thursday, August 18, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  487. Nuclear Physics & RIKEN Theory Seminar

    "Chiral Symmetry and meson gases: recent developments"

    Presented by Angel Gómez Nicola, Universidad Complutense, Madrid, Madrid

    Friday, August 12, 2011, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    "I will discuss some recent results on light meson gases, which may be of relevance for Heavy Ion and Nuclear Matter physics. These include thermal resonances and their relation to chiral symmetry restoration, chemical nonequilibrium effects, transport coefficients and isospin breaking. The basic framework is Chiral Perturbation Theory, which ensures the model independency of the low-energy and low-temperature regimes, combined with unitarity when an accurate analytical description of scattering is needed, as for the thermal width and transport coefficients. "

  488. HET/RIKEN Lunch Seminar

    "Detecting Fourth Generation Heavy Quarks at the LHC"

    Presented by David Atwood, Iowa State University

    Friday, August 5, 2011, 12 pm
    Building 510 / Room 2-160

    Hosted by: Amarjit Soni

  489. RIKEN Lunch Seminar

    "Interquark potential for the charmonium system with almost physical quark masses"

    Presented by Taichi Kawanai, University of Tokyo

    Thursday, August 4, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  490. Nuclear Physics & RIKEN Theory Seminar

    "Angular correlations in gluon emission ("ridge") from high energy QCD"

    Presented by Michael Lublinsky, Ben Gurion University of the Negev

    Friday, July 29, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    I will discuss angular and rapidity correlations in two-particle inclusive production ("ridge") in pp and AA collisions. Such correlations arise naturally in the theory of high energy QCD. A new insight based on solutions of the Balitsky-Kovchegov equation will be presented.

  491. RIKEN Lunch Seminar

    "Asymptotic Safety and Lattice Quantum Gravity"

    Presented by John Laiho, Glasgow University

    Thursday, July 28, 2011, 12:30 pm
    Building 510 / Room 2-220

    Hosted by: Toru Kojo

  492. Nuclear Physics & RIKEN Theory Seminar

    "Acoustic oscillations in higher harmonics of Big and Little Bangs"

    Presented by Pilar Staig & Edward Shuryak, Stony Brook University

    Friday, July 22, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    We study the effect that initial state fluctuations have on final particle correlations in heavy ion collisions. More precisely, we focus on the propagation of initial perturbations on top of the expanding fireball using the conformal solution derived by Gubser and Yarom for central collisions. The hydrodynamic equations are solved by separation of variables and the solutions for different modes are added up to construct initial point-like perturbations, that are then allowed to evolve until freeze-out. The Cooper-Frye prescription is used to determine the final particle distribution. We present the two-particle correlation functions and their Fourier spectra obtained for different viscosities. We find that viscosity kills the higher harmonics, but that the Fourier spectra presents maxima and minima, similar to what is seen in the study of Cosmic Background Radiation. The difference between the first and the second maximum is used to estimate the viscosity of the medium.

  493. RIKEN Lunch Seminar

    "Chiral symmetry restoration in monolayer graphene induced by Kekule distortion"

    Presented by Yasufumi Araki, University of Tokyo

    Thursday, July 21, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  494. Nuclear Physics & RIKEN Theory Seminar

    "Nuclear Matter Properties, Clustering at the Nuclear Surface and Symmetry Energy"

    Presented by Qamar Usmani, University Malaysia Perlis, Malaysia

    Friday, July 15, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    We present a phenomenological theory of nuclei which incorporates clustering at the nuclear surface in a general form. The theory explains the recently reported large values of symmetry energy by Natowitz et al at low densities of nuclear matter and is fully consistent with the static properties of nuclei. In phenomenological way clusters of all sizes, shapes along with medium modifications are included. Nuclear matter properties are discussed in detail. Arguments are given which lead to an equation of state of nuclear matter consistent with clustering. As a framework, an extended version of Thomas Fermi theory is adopted. This connects the nuclear matter equation of state, which incorporate clustering at low densities, with clustering in nuclei at the nuclear surface. Calculations are performed for various equation of state of nuclear matter consistent with clustering. The importance of quartic term in symmetry energy is demonstrated at and below the saturation density in nuclear matter. It is shown that it is related both to clustering as well as to the contribution of three-nucleon i nteraction to the equation of state of neutron matter. Reasons for these are discussed. Merits of the results with clustering and no-clustering are discussed. Due to clustering the neutron skin thickness in nuclei, fundamental to neutron star studies, is found to reduce significantly. An estimate of the spinodal density of symmetric nuclear matter is given. Theory predicts new situations and regimes to be explored both theoretically and experimentally.

  495. Nuclear Physics & RIKEN Theory Seminar

    "High-energy Amplitudes and Impact Factors at next-to-leading-order"

    Presented by Giovanni Chirilli, Lawrence Berkeley National Laboratory

    Friday, July 8, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Zhong-Bo Kang

    I will review the calculation of the high-energy amplitudes and impact factors in QCD and in N =4 SYM theory at next-to-leading order using the operator product expansion in terms of composite Wilson line operators.

  496. HET/RIKEN Lunch Seminar

    ""Chiral Polarization Properties of QCD Dirac Eigenmodes""

    Presented by Ivan Horvath, Kentucky

    Friday, July 8, 2011, 12 pm
    Building 510 / Room 2-95

    Hosted by: A. Soni

  497. RIKEN Lunch Seminar

    "Color decoherence in QCD jets and gluon Cherenkov radiation in dense medium"

    Presented by Andrey Leonidov, Lebedev Institute

    Thursday, July 7, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  498. High-Energy Physics & RIKEN Theory Seminar

    "The photon number integral"

    Presented by Leo Stodolsky, Max Planck, Munich

    Wednesday, July 6, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Amarjit Soni

  499. Nuclear Physics & RIKEN Theory Seminar

    "Hadron structure from exclusive measurements"

    Presented by Adam Szczepaniak, Indiana University

    Friday, July 1, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    The is a renewed interest in exclusive reactions. Electromagnetic form factors and Generalized Parton Distribution are examples of hadronic properties to be accessed in exclusive, photon induced transitions. I will discuss old and new ideas on partonic description of such properties.

  500. HET/RIKEN Lunch Seminar

    "TBA"

    Presented by Eigo Shintani, RBRC

    Friday, July 1, 2011, 12 pm
    Building 510 / Room 2-160

    Hosted by: Amarjit Soni

  501. RIKEN Lunch Seminar

    "The phase diagram in T-mu-Nc space"

    Presented by Giorgio Torrieri, Frankfurt University

    Thursday, June 30, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  502. High-Energy Physics & RIKEN Theory Seminar

    "Recent Results of the CRESST Dark Matter Search"

    Presented by Leo Stodolsky, The Max Planck Institute

    Wednesday, June 29, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Amarjit Soni

  503. RIKEN Lunch Seminar

    "4th generation & 2HDMs - Models for TeV-scale compositeness"

    Presented by Shaouly Bar-Shalom, Technion

    Friday, June 24, 2011, 12 pm
    Building 510 / Room 2-160

    Hosted by: Amarjit Soni

  504. RIKEN Lunch Seminar

    "Interweaving Chiral Spirals at large density"

    Presented by Toru Kojo, RBRC

    Thursday, June 23, 2011, 12:30 pm
    Building 510 / Room 2-160

  505. High-Energy Physics & RIKEN Theory Seminar

    "The Top Forward-Backward Asymmetry at Tevatron and the LHC"

    Presented by Jessie Shelton, Yale University

    Wednesday, June 15, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Amarjit Soni

  506. Nuclear Physics & RIKEN Theory Seminar

    "Testing NRQCD factorization in J/Psi production at NLO"

    Presented by Bernd Kniehl, Hamburg University

    Friday, June 3, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

  507. RIKEN Lunch Seminar

    "Lattice QCD meets experiment"

    Presented by Christine Davies, University of Glasgow

    Thursday, May 19, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  508. High-Energy Physics & RIKEN Theory Seminar

    "Flavor transitions in two Higgs doublet models"

    Presented by Stefania Gori, University of Chicago

    Wednesday, May 18, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Hye-Sung Lee

  509. Nuclear Physics & RIKEN Theory Seminar

    "Transverse momentum distributions from effective field theory"

    Presented by Prof. Frank Petriello, Northwestern University & Argonne National Laboratory

    Friday, May 6, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    We present an approach to the resummation of low transverse-momentum logarithms using Soft-collinear Effective Theory. This method naturally avoids several problems that affect the standard approach. After motivating the importance of this phase-space region for experimental analyses, we explain the approach. Numerical results and a discussion of the open issues are presented.

  510. RIKEN Lunch Seminar

    "Isospin breaking and chiral symmetry restoration"

    Presented by Ricardo Torres Andrés, Madrid University

    Thursday, May 5, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  511. Nuclear Physics & RIKEN Theory Seminar

    "Quark matter conductivity in strong magnetic field"

    Presented by Boris Kerbikov, ITEP, Moscow, Russia

    Friday, April 29, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    Recently it was realized that heavy-ion collisions generate a gigantic magnetic field.It has been argued that the relaxation time of this field crucially depends on electrical conductivity of quark matter.A related quantity,namely chiral conductivity,plays the central role in Chiral Magnetic Effect. Using ideas and methods developed in condensed matter physics we derive equations for quantum conductivity in three and two dimensions( d=2 corresponds to Lorentz contracted ions) with magnetic field varying from zero to maximal RHIC values. We believe that the results remain true beyond the simple model used in their derivation.

  512. RIKEN Lunch Seminar

    "PNJL model and imaginary chemical potential"

    Presented by Koji Kashiwa, (RBRC)

    Thursday, April 28, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  513. Nuclear Physics & RIKEN Theory Seminar

    "Recent Observations of and Theoretical Implications for Neutron"

    Presented by Jim Lattimer, Stony Brook University

    Friday, April 22, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    Recent observations of neutron stars in radio, visible and X-ray radiation are able to significantly constrain the properties of cold, dense matter. These observations include the discovery of a nearly 2 solar mass neutron star from pulsar timing, simultaneous mass and radius estimates from X-ray bursters and cooling quiescent stars, and detection of the rapid cooling of the Cassiopeia A supernova remnant. These have limited the range of equations of state for neutron star matter and severely restrict the roles that quark matter has in their interiors. Limits to the critical temperatures for a neutron superfluid and a proton superconductor in the core of neutron stars are also suggested.

  514. High-Energy Physics & RIKEN Theory Seminar

    "Heavy-light meson decays from HPQCD"

    Presented by Heechang Na, Ohio State University

    Wednesday, April 20, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Oliver Witzel

  515. High-Energy Physics & RIKEN Theory Seminar

    "New Perspectives on Dark Matter-Baryon Coincidence"

    Presented by Yanou Cui, Harvard University

    Wednesday, April 13, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Hye-Sung Lee

  516. RIKEN Lunch Seminar

    "TBA"

    Presented by Joachim Bartels, Hamburg University

    Thursday, April 7, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  517. High-Energy Physics & RIKEN Theory Seminar

    "Warped Radion Dark Matter"

    Presented by Eduardo Pontón, Columbia University

    Wednesday, April 6, 2011, 3:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Thomas McElmurry

    TBA

  518. Nuclear Physics & RIKEN Theory Seminar

    "Gauge symmetry and spin structure of the proton"

    Presented by Xiangdong Ji, University of Maryland

    Wednesday, April 6, 2011, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    Recently, there has been a flurry of activities about gauge symmetry constraints on the spin structure of the proton. I will discuss the new proposals.

  519. Nuclear Physics & RIKEN Theory Seminar

    "Orbifold equivalence in large-N QCD with finite baryon chemical potential and the sign problem"

    Presented by Masanori Hanada, University of Washington, Seattle

    Friday, April 1, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    We point out that large-N_c QCD in the 't Hooft limit is equivalent to SO(2*N_c) Yang-Mills theory with fundamental fermions. In the latter, notorious "sign problem" is absent even with finite baryon chemical potential, and hence the Monte-Carlo simulation is applicable. We also show the same idea can be applied in related models -- chiral random matrix theory (RMT) and holographic models. We explain nice old results like the exactness of the phase quenching in RMT in a certain parameter region is naturally understood and is generalized from the point of view of the equivalence. This talk is based on works with A. Cherman and D. Robles-Llana (Phys. Rev. Lett. 106, 091603), with N. Yamamoto (in preparation) and with C. Hoyos, A. Karch and L. Yaffe (in preparation).

  520. High-Energy Physics & RIKEN Theory Seminar

    "Electromagnetic Splitting of Charged and Neutral Mesons"

    Presented by Aaron M. Torok, Indiana University

    Wednesday, March 30, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Oliver Witzel

    We calculated the electromagnetic splittings of charged and neutral mesons, and the violation of Dashen's theorem. The meson masses are calculated with Lattice QCD using the MILC ensembles. U(1) gauge fields are generated independently. The computationally intensive part of the SU(3)xU(1) calculation is done using an implementation of the MILC staggered multi-mass inverter that originally ran on one GPU, and now runs on many. An extrapolation to the physical point is underway using staggered chiral perturbation theory.

  521. Nuclear Physics & RIKEN Theory Seminar

    "Onset of hydrodynamical flow from quantum fluctuations in a system of strong fields"

    Presented by Francois Gelis, CEA Saclay, France

    Friday, March 25, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

  522. HET/RIKEN Lunch Seminar

    "Generic dark matter signature for gamma-ray telescopes"

    Presented by Wai-Yee Keung, University of Illinois, Chicago

    Friday, March 25, 2011, 12 pm
    Building 510 / Room 2-160

    Hosted by: A. Soni

    We describe a characteristic signature of dark matter (DM) annihilation or decay into gamma-rays. We show that if the total angular momentum of the initial DM particle(s) vanishes, and helicity suppression operates to prevent annihilation/decay into light fermion pairs, then the amplitude for the dominant 3-body final state e+e- gamma has a unique form dictated by gauge invariance. This amplitude and the corresponding energy spectra hold for annihilation of DM Majorana fermions or self-conjugate scalars, and for decay of DM scalars, thus encompassing a variety of possibilities. Within this scenario, we analyze Fermi LAT, PAMELA and HESS data, and predict a hint in future Fermi gamma-ray data that portends a striking signal at atmospheric Cherenkov telescopes (ACTs).

  523. RIKEN Lunch Seminar

    "Anisotropic flow in event-by-event viscous hydrodynamics"

    Presented by Bjoern Schenke, BNL

    Thursday, March 24, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  524. High-Energy Physics & RIKEN Theory Seminar

    "Large-N QCD from simulations on a single site?"

    Presented by Steve Sharpe, University of Washington

    Wednesday, March 23, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Oliver Witzel

  525. Nuclear Physics & RIKEN Theory Seminar

    "Viscous hydrodynamic radial and elliptic flow from RHIC to LHC"

    Presented by Chun Shen, Ohio State University

    Friday, March 18, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    Using viscous hydrodynamics and a state-of-the-art equation of state,s95p-PCE, we explore the dependence of the final observed hadron spectra and elliptic flow on the input parameters, in particular shear viscosity. Based on these experiences, we present an excellent fit for the spectra and elliptic flow of all charged hadrons as well as identified pions and protons from Au+Au collisions of all centralities measured at the relativistic Heavy Ion Collider (RHIC). Taking this global fit as starting point, we extrapolate to higher Large Hadron Collider (LHC) energies and predict the analogous observables for Pb+Pb collisions at √s =2.76 and 5.5ATeV, assuming the same constant specific shear viscosity η/s and thermalization time at both collision energies. Comparison with recent ALICE measurements of the elliptic flow of charged hadrons shows that the model slightly overpredicts the data. This indicates some possible temperature dependence of (η/s)(T), and I will show some results when I explain this possibility. Future experiments will further test the model and shed additional light on possible variations of the quark-gluon transport coefficients between RHIC and LHC energies.

  526. Nuclear Physics & RIKEN Theory Seminar

    "QCD and Beyond on the Lattice"

    Presented by Meifeng Lin, Yale University

    Friday, March 11, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    The theory that describes strong interactions between quarks and gluons, quantum chromodynamics (QCD), has a coupling strength that is stronger at low energies, making it implausible to study low-energy physics using perturbation theory. Discretizing it on a space-time lattice is the only known way to study strong interactions from first principles. I will give an overview of lattice QCD and focus on its applications in nucleon structure calculations. Using the lattice approach to study other QCD-like theories will also be briefly discussed.

  527. RIKEN Lunch Seminar

    "TBA"

    Presented by Andrej Ficnar, Columbia University

    Thursday, March 10, 2011, 12:30 pm
    Building 510 / Room 2-160

  528. Joint HET/RIKEN/YITP Seminar

    "String Theory and the Real World"

    Presented by Herman Verlinde, Princeton University

    Wednesday, March 9, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  529. Nuclear Physics & RIKEN Theory Seminar

    "Jet Tomography and Particle Correlations in Heavy-Ion Collisions"

    Presented by Barbara Betz, Columbia University

    Friday, March 4, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    Heavy-ion collisions offer the possibility to study matter under extreme conditions of high temperatures and densities in the laboratory. Jets and jet-medium correlations can probe the high-energy-density matter created in such collisions. Azimuthal correlations suggest that conical wakes are induced and have been interpreted as evidence for the creation of Mach cones due to the propagation of a supersonic parton. In this talk, the efforts and the progress in understanding the medium response to the propagation of a supersonic jet will be critically reviewed and the recent developments will be reported. Moreover, the sensitivity of the azimuthal dependence of single and dihadron nuclear modification factors to the fluctuation spectrum of initial geometric inhomogeneities will be investigated comparing Glauber and KLN Monte Carlo models, leading into a discussion on how average azimuthal moments could help to differentiate between the geometrical ensembles.

  530. RIKEN Lunch Seminar

    "The anisotropy flows in viscous hydrodynamics"

    Presented by Li Yan, Stony Brook University

    Thursday, March 3, 2011, 12:30 pm
    Physics, Room 2-160

    Hosted by: Anthony Baltz

  531. High-Energy Physics & RIKEN Theory Seminar

    "A new perspective on CP violation in three body decays"

    Presented by Monika Blanke, Cornell University

    Wednesday, March 2, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: A. Soni

    I discuss the potential of measuring CP violation in three body decays, paying particular attention to the different possible origins of the "strong" CP-even phase. This phase can be obtained from the propagation of intermediate state particles - either when diagrams with different intermediate particles interfer, or when the intermediate state is off-shell by a different amount. I will elaborate mainly on the second case here which has not yet received much attention in the literature. After analysing a simple toy model I apply our findings to a specific example, namely neutralino decay in the MSSM.

  532. Nuclear Physics & RIKEN Theory Seminar

    "Holography and the collision of gravitational waves in asymptotically AdS_5 spacetime"

    Presented by Paul Chesler, MIT

    Friday, February 25, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: G. Beuf

    In recent years holography has emerged as a powerful tool to study non-equilibrium phenomena in certain quantum theories, mapping challenging quantum dynamics onto the classical dynamics of gravitational fields in one higher dimension. One interesting process which can be addressed with holography is the collision of sheets of matter in strongly coupled non-Abelian gauge theories. The collision results in the creation of a quark-gluon plasma which at late times behaves as a nearly ideal liquid. In the dual gravitational description, this process maps onto the process of gravitational collapse and black hole formation in asymptotically AdS_5 spacetime. I will describe how one can use techniques from numerical relativity to study this process.

  533. High-Energy Physics & RIKEN Theory Seminar

    "No-Scale F-SU(5)"

    Presented by Tianjun Li, Texas A&M

    Wednesday, February 23, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: A. Soni

  534. Special Nuclear Theory/RIKEN Seminar

    "Long range rapidity correlations in azimuthal angle for pp and AA"

    Presented by Eugene Levin, Tel Aviv University

    Thursday, February 17, 2011, 12:30 pm
    Building 510 / Room 2-160

    Hosted by: Toru Kojo

  535. High-Energy Physics & RIKEN Theory Seminar

    "Exotic Dark Matter at Colliders from Proton Stability"

    Presented by Kaustubh Agashe, University of Maryland

    Wednesday, February 16, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: A. Soni

  536. Nuclear Theory/Riken Seminar

    "Diagrammatic method for computing transport coefficients near the chiral phase transition"

    Presented by Yoshimasa Hidaka, Kyoto University

    Friday, February 11, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    We propose a novel diagrammatic method for computing transport coefficients in relativistic quantum field theory. The self-consistent equation for summing the diagrams with pinch singularities has a form of a linearized kinetic equation as usual, but our formalism enables us to incorporate higher oder corrections of the coupling systematically. We apply our formalism to a simple model with chiral symmetry, and discuss the behavior of the transport coefficients around the chiral phase transition at finite temperature.

  537. Riken Lunch Seminar

    "Spectrum of the Wilson Dirac Operator"

    Presented by Jacobus Verbaarschot, Stony Brook University

    Thursday, February 10, 2011, 12:30 pm
    Physics Building Rom 2-160

    Hosted by: Toru Kojo

  538. High-Energy Physics & RIKEN Theory Seminar

    "Exploring 8 and 12 Flavor QCD"

    Presented by Robert Mawhinney, BNL

    Wednesday, February 9, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Oliver Witzel

    QCD with many light quark flavors may have a conformal phase, before the theory loses asymptotic freedom. We report on extensive simulations of 8 and 12 flavor QCD, where we have measured light hadron masses, decay constants and the string tension at zero temperature. We have also observed the finite temperature transition for 8 flavors and seen that it is first order. This data supports 8 and 12 flavor QCD being in the conventional, chirally broken phase, in contrast to other studies measuring the beta function.

  539. Nuclear Physics & RIKEN Theory Seminar

    "Jets, Mach-cone, hot spots, ridges and harmonic flow - the landscape in dihadron correlation"

    Presented by Xin-Nian Wang, LBNL

    Friday, January 28, 2011, 2 pm
    Small Seminar Room, Bldg. 510

    Fluctuations in initial parton production in high-energy heavy-in collisions lead to irregular initial transverse energy density distribution with hot spots and valleys that are also extended in rapidity. These irregular initial density distribution will lead to finite harmonic flow in hadron distribution through collective expansion even in the most central heavy-ion collisions. I will discuss dihadron correlations from dijets, jet-induced Mach-cone and expanding hot spots, after subtraction of contributions from harmonic flow. Comparison between dihadron and gamma-hadron correlation will further differentiate correlations from Mach-cone and expanding hot spots. The ridge-like structure of these net diahdron correlation in the longitudinal direction is also discussed

  540. Joint HET/RIKEN/YITP Seminar

    "TBA"

    Presented by Patrick Meade, YITP

    Friday, January 28, 2011, 12 pm
    Building 510 Room 2-160

    TBA

  541. Riken Lunch Seminar

    "TBA"

    Presented by Bjoern Schenke, BNL

    Thursday, January 27, 2011, 12:30 pm
    Physics Building Rom 2-160

    TBA

  542. Lunch Seminar

    "Estimating thermal dilepton rate and electrical conductivity Heng-Tong Ding (BNL) RIKEN Lunch seminar"

    Presented by Heng-Tong Ding, BNL

    Thursday, January 20, 2011, 12:30 pm
    Physics Building Rom 2-160

    TBA

  543. High-Energy Physics & RIKEN Theory Seminar

    Presented by Jay Wacker, SLAC

    Tuesday, January 11, 2011, 2 pm
    Small Seminar Room, Bldg. 510

  544. Nuclear Physics & RIKEN Theory Seminar

    "Universal relation for strong interacting atoms"

    Presented by Daekyoung Kang, The Ohio State University

    Tuesday, January 11, 2011, 11 am
    Small Seminar Room, Bldg. 510

  545. High-Energy Physics & RIKEN Theory Seminar

    "LHC@BNL"

    Monday, January 10, 2011, 9:30 am
    Large Seminar Room, Bldg. 510

  546. Nuclear Physics & RIKEN Theory Seminar

    "Deconfinement in Yang-Mills theory through toroidal"

    Presented by Mithat Unsal, Stanford University

    Friday, December 10, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    We introduce field theory techniques through which the deconfinement transition of four-dimensional Yang-Mills theory can be moved to a semi-classical domain where it becomes calculable using two-dimensional field theory. The two dimensional theory has electric and magnetic (order and disorder) perturbations, analogs of which appear in planar spin-systems and statistical physics. In this regime, the deconfinement transition is driven by the competition between electric and magnetic perturbations.

  547. Nuclear Physics & RIKEN Theory Seminar

    "TBA"

    Presented by Yannis Burnier, Stony Brook

    Thursday, December 9, 2010, 12:30 pm
    Building 510A Room 2-160

    TBA

  548. High-Energy Physics & RIKEN Theory Seminar

    "Heavy Octets and Tevatron Signals with Three or Four b jets"

    Presented by Yang Bai, SLAC

    Wednesday, December 8, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Hye Sung Lee

  549. Nuclear Physics & RIKEN Theory Seminar

    "Thermal Quark and Gluon Distributions in the PNJL model"

    Presented by Hung-Ming Tsai, Duke University

    Friday, December 3, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    In this talk, we explore the dynamics of gluons in the Nambu-Jona-Lasinio model with Polyakov loop (PNJL model) within the mean-field approximation. We first calculate the fundamental Polyakov loop by minimizing the PNJL action and then obtain the adjoint Polyakov loop by demanding self-consistency with the Gocksch-Ogilvie effective action for the eigenvalues of the Polyakov loop. We then derive the quark and gluon number densities and other thermodynamic quantities as functions of temperature and chemical potential. We explain why the deconfinement transition is much faster for light quarks than for gluons

  550. RIKEN Lunch Seminar

    "Waves of anomaly in QGP"

    Presented by Ho-Ung Yee, Stony Brook

    Thursday, December 2, 2010, 12 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  551. High-Energy Physics & RIKEN Theory Seminar

    "Looking for the Origin of Neutrino Masses: from neV to YeV"

    Presented by A. de Gouvea, Northwestern University

    Wednesday, December 1, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  552. Nuclear Physics & RIKEN Theory Seminar

    "Jet quenching in DIS and heavy-ion collisions: moving towards a more quantitative approach"

    Presented by Abhijit Majumdar, Ohio State University

    Thursday, November 18, 2010, 12:30 pm
    Bldg 510, room 2-220

    Hosted by: Rob Pisarski

    The modification of hard jets in dense extended media such as large nuclei or a deconfined quark gluon plasma will be described in a factorized formalism where the hard partons couple weakly with the medium, where the medium may itself be strongly or weakly coupled. The effect of the medium will be parametrized in a handful of transport coefficients which are obtained as the in-medium expectation of well defined operator products. We will attempt to describe the attenuation of the yield of leading hadrons in DIS and heavy-ion collisions (HIC) as well as the centrality, azimuthal anisotropy and flavor dependence (in HIC) in a single formalism. Also preliminary results from a new Monte-Carlo event generator based on this formalism will be presented.

  553. Nuclear Physics & RIKEN Theory Seminar

    "High-pT v2 and path-length dependence of energy loss in QCD"

    Presented by Cyrille Marquet, CERN

    Friday, November 12, 2010, 2 pm
    Small Seminar Room, Bldg. 510

  554. High-Energy Physics & RIKEN Theory Seminar

    "Monopoles, bions, and other oddballs in confinement or conformality"

    Presented by Erich Poppitz, University of Toronto

    Wednesday, November 10, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Oliver Witzel

    I will explain how compactification on a small (non-thermal) circle yields a regime where the study of supersymmetric and nonsupersymmetric nonperturbative gauge dynamics comes under theoretical control. I will review recent developments in this area and discuss possible directions for future work.

  555. Nuclear Physics & RIKEN Theory Seminar

    "pi deuteron effective mass correlation as a probe hadron gas density"

    Presented by Ron Longacre, BNL

    Friday, November 5, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Guillame Beuf

  556. Riken Lunch Seminar

    "The topolotical facet of strongly coupled quark-gluon plasma"

    Presented by Jinfeng Liao, BNL

    Thursday, November 4, 2010, 12:30 pm
    Building 510A Room 2-160

    TBA

  557. High-Energy Physics & RIKEN Theory Seminar

    "The Dark Matter - LHC Connection: A few model-independent statements"

    Presented by Can Kilic, Rutgers

    Wednesday, November 3, 2010, 2:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: A.Soni

  558. Joint HET/RIKEN/YITP Seminar

    "TBA"

    Presented by Walter Goldberger, Yale

    Wednesday, October 20, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    TBA

  559. Nuclear Physics & RIKEN Theory Seminar

    "Dilemma of Ads /QCD"

    Presented by Hans-Juergen Pirner, Institut fuer Theoretische Physik, Heidelberg, Germany

    Friday, October 15, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

  560. HET/RIKEN Seminar

    "Improving and Expanding Searches for TeV-Scale Z' Bosons Decaying to WW and Zh"

    Presented by Brock Tweedie, Boston University

    Thursday, October 14, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  561. High-Energy Physics & RIKEN Theory Seminar

    "Improving and Expanding Searches for TeV-Scale Z' Bosons Decaying to WW and Zh"

    Presented by Brock Tweedie, Boston University

    Thursday, October 14, 2010, 12:30 pm
    Room 2-160, Bldg 510

    Hosted by: T. McElmurry

  562. High-Energy Physics & RIKEN Theory Seminar

    "Flavor oscillations of supernova neutrinos and the observation of the neutrino signal in the DUSEL detector"

    Presented by Alexander Friedland, Los Alamos National Laboratory

    Wednesday, October 6, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Hooman Davoudiasl

  563. Nuclear Physics & RIKEN Theory Seminar

    "k_t-factorization for hard processes in nuclei"

    Presented by Fabio Dominguez, Columbia University

    Friday, October 1, 2010, 1 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    Two widely proposed $k_t$-dependent gluon distributions in the small-$x$ saturation regime are investigated using two particle back-to-back correlations in high energy scattering processes. The Weizs\"{a}cker-Williams gluon distribution, interpreted as the number density of gluons inside the nucleus, is studied in the quark-antiquark jet correlation in deep inelastic scattering. On the other hand, the unintegrated gluon distribution, defined as the Fourier transform of the color-dipole cross section, is probed in the direct photon-jet correlation in $pA$ collisions. Dijet-correlation in $pA$ collisions depends on both gluon distributions through combination and convolution in the large $N_c$ limit. We calculate these processes in two approaches: the transverse momentum dependent factorization approach and the color-dipole/color glass condensate formalism, and they agree with each other completely.

  564. Nuclear Physics & RIKEN Theory Seminar

    "Better understanding the relation between the JIMWLK Hamiltonian and the BFKL limit"

    Presented by Alex Kovner, University of Connecticut

    Wednesday, September 22, 2010, 3:15 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    I discuss the relation between the eigenfunctions and eigenvalues of the JIMWLK Hamiltonian and those of its low density limit - the BFKL Hamiltonian. I show that the eigenfunctions get corrections in the perturbation theory (expansion in powers of the charge density), while the eigenvalues do not. I also explain how the bootstrap condition arises automatically from the JIMWLK/KLWMIJ framework as direct consequence of the hermiticity of the Hamiltonian. Leading correction to the BFKL reggeized gluon wave function is calculated.

  565. Joint HET/RIKEN/YITP Seminar

    "BSM theory review of solutions to the Top quark forward-backward asymmetry anomaly at Tevatron"

    Presented by Kai Wang, IPMU, The University of Tokyo

    Wednesday, September 22, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    TBA

  566. High-Energy Physics & RIKEN Theory Seminar

    "BSM theory review of solutions to the Top quark forward-backward asymmetry anomaly at Tevatron"

    Presented by Kai Wang, IPMU, The University of Tokyo, Japan

    Wednesday, September 22, 2010, 2 pm
    Small Seminar Room, Bldg. 510

  567. RIKEN Lunch Seminar

    "Lattice Study of Flavor SU(3) Breaking in Hyperon Beta Decays"

    Presented by Shoichi Sasaki, University of Tokyo, Japan

    Thursday, September 9, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  568. Nuclear Physics & RIKEN Theory Seminar

    "'An effective chiral Equation of State including hadronic and quark degrees of freedom"

    Presented by Jan Steinheimer-Froschauer, Goethe University Frankfurt, Germany

    Friday, September 3, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    We combine, in a single model, a well-established flavor-SU(3) hadronic model with a quark-gluon description of the highly excited matter. This allows us to study the chiral-symmetry and confinement-deconfinement phase structure of strongly interacting matter at high temperatures and densities. In addition we obtain an equation of state of hadronic and quark matter that is applicable over a wide range of thermodynamical conditions. I will present results on the thermodynamics of the model, compared to recent lattice data, as well as the phase structure in temperature and baryochemical potential. In this context I will also highlight the influence of heavy hadronic resonances on the chiral phase transition. Furthermore I will discuss the temperature dependence of the baryon number susceptibilities for different parametrizations of the model and compare the results to lattice data and results obtained with a basic PNJL model.

  569. Nuclear Physics & RIKEN Theory Seminar

    "Monte-Carlo simulation of heavy-ion collisions"

    Presented by Bjoern Schenke, McGill University

    Friday, August 27, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    I present the Modular Algorithm for Relativistic Treatment of heavy IoN Interactions (MARTINI), a Monte-Carlo simulation of high energy heavy-ion collisions. Its main components are PYTHIA 8.1, a time evolution model for the soft background, and a parton evolution scheme, currently the McGill-AMY formalism including radiative as well as elastic processes. MARTINI generates full event configurations in the high p_T region that take into account thermal QCD and QED effects as well as effects of the evolving medium. I will show latest results for hard observables in Au+Au and Cu+Cu collisions at RHIC energies, using different fluid-dynamic calculations for the soft background evolution. I further present first correlation studies and discuss MARTINI's potential to provide input for full jet reconstruction algorithms.

  570. Nuclear Physics & RIKEN Theory Seminar

    "ETQS matrix element and the sign reversal of the Sivers function"

    Presented by Andreas Metz, Temple University

    Friday, August 20, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    The twist-3 ETQS (Efremov-Teryaev-Qiu-Sterman) matrix element, which has a direct relation to the Sivers parton distribution, plays a very important role in the phenomenology of transverse single spin asymmetries measured at RHIC in proton-proton collisions. We discuss new results showing that the ETQS matrix element can also be addressed, for instance, in e+p --> jet+X in a rather clean way. This matrix element also shows up e+when describing transverse single spin asymmetries for W-production at RHIC. It is argued that the latter observable is very promising in order to check the predicted sign reversal of the Sivers function.

  571. Joint HET/RIKEN Lunch Seminar

    "Nucleon physics on the lattice"

    Presented by Meifeng Lin Lin, Yale University

    Thursday, August 19, 2010, 12:30 pm
    Building 510A Room 2-160

  572. Nuclear Physics & RIKEN Theory Seminar

    "Strong to weak coupling transition in large Nc QCD"

    Presented by Rajamani Narayanan, Florida International University

    Friday, August 6, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    "Two-dimensional chiral fermions coupled to four dimensional gauge fields will be used as a probe to properly quantify the large Nc strong to weak coupling transition."

  573. RIKEN Lunch Seminar

    "Charmonium-nucleon Interaction from Lattice QCD"

    Presented by Taichi Kawanai, University of Tokyo, Japan

    Thursday, August 5, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  574. Nuclear Physics & RIKEN Theory Seminar

    "The nuclear liquid-gas phase transition at large $N_c$ in the Van der Waals approximation"

    Presented by Giorgio Torrieri, Columbia University

    Friday, July 30, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    The nuclear liquid-gas phase transition at large $N_c$ in the Van der Waals approximation We examine the nuclear liquid-gas phase transition at large number of colors ($N_c$) within the framework of the Van Der Waals (VdW) model. We argue that the VdW equation is appropriate at describing inter-nucleon forces , and discuss how each parameter scales with $N_c$. We demonstrate that $N_c=3$ is not large with respect to the other dimensionless scale relevant to baryonic matter, the number of neighbours in a dense system. Consequently, we show that the liquid-gas phase transition looks dramatically different at $N_c \rightarrow \infty$ with respect of our world: The critical point temperature becomes of the order of $\lqcd$ rather than below it. The critical point density becomes of the order of the baryonic density, rather than an order of magnitude below it. These are precisely the characteristics usually associated with the ``Quarkyonic phase''. We therefore argue that at large $N_c$ the nuclear liquid phase coincides with the conjectured quarkyonic phase, although the two are thought to occur at very different scales in our world.

  575. RIKEN Lunch Seminar

    "pi^0 to two photon decay on the lattice"

    Presented by Eigo Shintani, RBRC

    Thursday, July 29, 2010, 12:30 pm
    Bldg 510, Room 2-160

    Hosted by: Anthony Baltz

  576. Nuclear Physics & RIKEN Theory Seminar

    "Thermal Conductivity Of Quark Matter In The CFL Phase"

    Presented by Jingyi Chao, North Carolina State University

    Friday, July 23, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    I briefly review the formation of color superconductivity which happen in compact stars. Below the temperature scale set by the gap in the quark spectrum, transport properties are determined by collective modes. We compute the thermal conductivity, $\kappa$, of color-flavor locked (CFL) quark matter in the frame of kinetics theory. We present and compare the result with previous estimates. We also conclude a CFL quark matter core of the compact star becomes isothermal on a timescale of a few seconds.

  577. Nuclear Physics & RIKEN Theory Seminar

    "QCD with chemical potential in a small hyperspherical box"

    Presented by Joyce Meyers, Swansea University, UK

    Friday, July 9, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    We consider the phase diagram of QCD formulated in small spatial volumes. The benefit of the small spatial volume is that it allows for a perturbative calculation of the phase diagram which is valid for all temperatures and densities. The action of QCD is complex when the quarks are coupled to a non-zero chemical potential. This results in the sign problem which prevents lattice simulations using conventional techniques. From one-loop perturbation theory on S^1 x S^3 we calculate the phase diagram analytically in the T − mu plane in the large N and Nf limit by generalizing large N matrix model techniques for the case of a complex action. We compare with low temperature results for N = 3 obtained by performing the integrals over the gauge fields numerically. We calculate expectation values for several observables including the fermion number and the Polyakov lines. For the fermion number a Landau-level-like structure is observed as a function of the chemical potential and each level transition coincides with a spike in the Polyakov lines, indicating partial-filling of the level. In the large N limit each level transition corresponds to discontinuities in the fermion number which result in third-order transitions of the Gross-Witten-Wadia type. We confirm the appearance of the level-structure at low temperatures in lattice simulations of 2-color QCD where the sign problem is absent.

  578. Nuclear Physics & RIKEN Theory Seminar

    "Induced gluon radiation in QCD matter and jet quenching"

    Presented by Bronislav Zakharov, Landau Institute

    Friday, July 2, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    We discuss parton energy loss in QCD matter within the light-cone path integral approach to the induced gluon emission. In the first part of the talk we give a short introduction to the formalism. Then we discuss the radiative energy loss in a static brick of quark-gluon plasma. In the second part of the talk we present the results for the energy loss and jet quenching in expanding quark-gluon plasma for RHIC and LHC energies. At the end of the talk we discuss the anomalous baryon production and synchrotron energy loss.

  579. High-Energy Physics & RIKEN Theory Seminar

    "W-Z-top bags and baryogenesis"

    Presented by Edward Shuryak, Stony Brook University

    Wednesday, June 30, 2010, 2 pm
    Small Seminar Room, Bldg. 510

  580. Nuclear Physics & RIKEN Theory Seminar

    "Di-electron production from full 3D hydrodynamic model with spectral constraint"

    Presented by Yukinao Akamatsu, University of Tokyo, Japan

    Friday, June 25, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    The di-electron production from the medium in the low invariant mass region is calculated from the full 3D hydrodynamic model. The di-electron rate is related to the in-medium spectral function of vector modes. The vector spectral function in all temperature is modeled with a constraint from QCD sum rule. We show that the dependence of the di-electron spectra on the equation of state is large and that it is one of the main causes for the discrepancy between the theoretical calculation and the experimental data of di-electrons at PHENIX. We also point out that the contribution of the di-electrons produced from the bremsstrahlung in hadronic reaction is quite large below the two pion threshold.

  581. Special Nuclear Theory Seminar / RIKEN Lunch Seminar

    "Fun with flux loops in hot QCD"

    Presented by Chris Korthals Altes, Centre CNRS, Marseille, France, Netherlands

    Thursday, June 24, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  582. High-Energy Physics & RIKEN Theory Seminar

    "Living in Extra Dimensions"

    Presented by Argyris Nicolaidis, Aristotle University of Thessaloniki, Greece

    Wednesday, June 9, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Yannis Semertzidis

    In models unifying gravity and the other forces, gravity propagates, besides the usual four dimensions, into additional δ extra dimensions and gravity becomes strong at TeV energies. We look for signatures of extra dimensions and strong gravitational phenomena in cosmic rays, attributing the cosmic ray to produced gravitons, escaping in the extra dimensions LHC, with the production of microscopic black holes unconventional neutrino oscillations, where a flavor neutrino mixes with a singlet neutrino living in the bulk photon mixing with an axion living in extra dimensions, providing new explanations for the transparency of the universe to high energy photons and for the dispersion of time arrival of the MAGIC photons in cosmic rays, LHC physics, high energy neutrinos, and the astrophysics of high energy photons.

  583. Nuclear Physics & RIKEN Theory Seminar

    "Spectral Densities for Hot QCD Plasmas in a Leading-Log Approximation"

    Presented by Juhee Hong, SUNY Stony Brook

    Friday, June 4, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    The leading-log Boltzmann equation is solved numerically with non-trivial boundary conditions. We present the spectral densities of J^\mu and T^\mu\nu at small frequencies : current, shear, sound, bulk, and transverse tensor channel. They exhibit a smooth transition from free streaming quasi-particles to ideal hydrodynamics. This transition is analyzed with second order hydrodynamics and compared with AdS/CFT.

  584. High-Energy Physics & RIKEN Theory Seminar

    "Spontaneous Chiral Symmetry breaking on the Lattice"

    Presented by Shoji Hashimoto, KEK, Japan

    Wednesday, June 2, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: A Soni

  585. RIKEN Lunch Seminar

    "Using HERA Data to Determine the Infrared Behaviour of the BFKL Amplitude"

    Presented by Henri Kowalski, (DESY)

    Thursday, May 20, 2010, 12:30 pm
    Room 2-160

    TBA

  586. Nuclear Physics & RIKEN Theory Seminar

    "Viscosity of Strongly Interacting Fermi Gases"

    Presented by Mohit Randeria, Ohio State University

    Friday, May 14, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    Transport in strongly interacting systems, which may not support well-defined quasiparticle excitations, is a subject of great interest in diverse fields ranging from condensed matter physics to nuclear physics and string theory. In this talk I will describe recent work on the viscosity of non-relativistic quantum fluids, with a particular focus on strongly interacting ultracold Fermi gases. I will discuss exact nonperturbative results based on spectral functions and sum rules, and conclude with a proposal for a spectroscopic measurement of the shear viscosity spectral function in the unitary Fermi gas.

  587. RIKEN Lunch Seminar

    "Low-energy constants from Dirac eigenvalue correlators at NNLO in the epsilon expansion"

    Presented by Christoph Lehner, RBRC, Germany

    Thursday, May 6, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

    We calculate the next-to-next-to-leading order (NNLO) contributions in the epsilon expansion with a small imaginary chemical potential and discuss their relevance to Dirac eigenvalue correlators. We show how to minimize systematic deviations from random-matrix theory by an optimal choice of lattice geometry in the case of two light quark flavors. Finally, we determine the low-energy constants Sigma and F from configurations of JLQCD with two dynamical overlap fermions.

  588. Nuclear Physics & RIKEN Theory Seminar

    "Holographic approach for the effects of nuclear density and gluon condensation"

    Presented by Bumhoon Lee, Sogang University, Seoul, Korea

    Friday, April 30, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    We identify the dual geometry of the hadron phase of dense nuclear matter and investigate the confinement/deconfinement phase transition. We suggest that the low temperature phase of the RN black hole with the full backreaction of the bulk gauge field is described by the zero mass limit of the RN black hole with hard wall. We calculated the density dependence of critical temperature, meson masses and decay constants. We also describe the thermodynamics of the gluon condensation including the effect of the Hawking-Page transition

  589. Joint HET/RIKEN/YITP Seminar

    "Quantum Criticality and the Cuprate Superconductors"

    Presented by Subir Sachdev, Harvard University

    Wednesday, April 28, 2010, 2 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    I will begin with a simple introduction to the theory of quantum criticality, as applied to experiments on certain insulating antiferromagnets. I will then survey the phenomenology of the cuprate high temperature superconductors, and show how ideas from quantum criticality have helped explain or predict the results of a number of recent experiments. The applications to the cuprates focus attention on key problems associated with the criticality of Fermi surfaces in two dimensions which remain unresolved. I will describe how these open problems are being addressed by the AdS/CFT correspondence discovered in string theory.

  590. Nuclear Physics & RIKEN Theory Seminar

    "Comprehensive Solution to the Cosmological Constant, Zero-Point Energy, and Quantum Gravity Problems"

    Presented by Philip Mannheim, University of Connecticut

    Friday, April 23, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    We present a solution to the cosmological constant, the zero-point energy, and the quantum gravity problems within a single comprehensive framework. We show that in quantum theories of gravity in which the zero-point energy density of the gravitational field is well-defined, the cosmological constant and zero-point energy problems solve each other by mutual cancellation between the cosmological constant and the matter and gravitational field zero-point energy densities. Because of this cancellation, regulation of the matter field zero-point energy density is not needed, and thus does not cause any trace anomaly to arise. We exhibit our results in two theories of gravity that are well-defined quantum-mechanically. Both of these theories are locally conformal invariant, quantum Einstein gravity in two dimensions and Weyl-tensor-based quantum conformal gravity in four dimensions (a fourth-order derivative quantum theory of the type that Bender and Mannheim have recently shown to be ghost-free and unitary). Central to our approach is the requirement that any and all departures of the geometry from Minkowski are to be brought about by quantum mechanics alone. Consequently, there have to be no fundamental classical fields, and all mass scales have to be generated by dynamical condensates. In such a situation the trace of the matter field energy-momentum tensor is zero, a constraint that obliges its cosmological constant and zero-point contributions to cancel each other identically, no matter how large they might be. In our approach quantization of the gravitational field is caused by its coupling to quantized matter fields, with the gravitational field not needing any independent quantization of its own. With there being no a priori classical curvature, one does not have to make it compatible with quantization.

  591. RIKEN Lunch Semianr

    "QCD Phase Structure and Imaginary Endpoints"

    Presented by Massimo D'Elia, Genoa University

    Thursday, April 22, 2010, 12:30 pm
    Building 510 Room 2-160

  592. RIKEN Lunch Seminar

    "QCD Phase Structure and Imaginary Endpoints"

    Presented by Massimo D'Elia, Genoa University, Italy

    Thursday, April 22, 2010, 12:30 pm
    Bldg 510, Rm 2-160

    Hosted by: Anthony Baltz

  593. High-Energy Physics & RIKEN Theory Seminar

    "Walking Step by Step on the Lattice"

    Presented by David Lin, NCTS & National Chiao-Tung University

    Wednesday, April 21, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: A. Soni

  594. Nuclear Physics & RIKEN Theory Seminar

    "Collision geometry fluctuations and triangular flow in heavy-ion collisions"

    Presented by Burak Alver, MIT

    Friday, April 16, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    It was suggested that fluctuations in the initial geometry of ultrarelativistic heavy ion collisions can provide an explanation for the surprisingly large elliptic flow values observed in central Cu+Cu collisions. Measurement of elliptic flow fluctuations in Au+Au collisions has confirmed the existence of such large geometry fluctuations. In this talk, I will discuss how the same principle of initial geometry fluctuations may also be the key to understanding the "ridge" and "broad away side" structures present in two particle correlation measurements. I will introduce the concepts of participant triangularity and triangular flow, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multi-phase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Ratios of the second and third Fourier coefficients of two particle azimuthal correlations are observed to exhibit similar trends in experimental data and AMPT calculations as a function of centrality and transverse momentum, suggesting a similar origin. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.

  595. RIKEN Lunch Seminar

    "The Neutral Kaon Mixing Parameter from Lattice QCD"

    Presented by Jack Laiho, University of Glasgow

    Thursday, April 15, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  596. High-Energy Physics & RIKEN Theory Seminar

    "SUSY and Hidden Sector Extensions with Dark Matter and LHC Signatures"

    Presented by Daniel Feldman, University of Michigan

    Wednesday, April 14, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Discussed are high scale models of supersymmetry and hidden sector extensions of the minimal framework. LHC signatures of new physics are connected to recent data driven probes of dark matter scattering. Implications for the annihilation of dark matter in the galaxy are also discussed including proposed solutions to the cosmic anomalies reported in the PAMELA Satellite data.

  597. Nuclear Physics & RIKEN Theory Seminar

    "Is the scaling of v2 in heavy ion collisions natural?"

    Presented by Giorgio Torrieri, JW Goethe Universitaet, Frankfort, Germany

    Friday, April 9, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    We examine the "naturalness" of the scaling of multiplicity and elliptic flow $v_2$ with rapidity in weakly and strongly coupled systems. We show that multiplicity scaling is relatively straight-forward to incorporate in existing ansatze with no unnatural assumptions, and argue that this scaling is relatively insensitive to the transport properties of the system. On the other hand, we argue that the observed scaling of elliptic flow observed is problematic to describe within a hydrodynamic model (the Knudsen number $K \ll 1$), but arises more naturally within weakly coupled systems (where the Knudsen number $\sim 1$). We conclude by an overview of ways proposed to make weakly coupled systems compatible with the absolute value of elliptic flow, and by indicating experimental probes which could clarify these issues

  598. High-Energy Physics & RIKEN Theory Seminar

    "A Dark Matter Explanation of the Fermi, PAMELA, and WMAP Results"

    Presented by Lisa Goodenough, New York University

    Wednesday, April 7, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Ruth Van der Water

    Multiple lines of evidence indicate an anomalous injection of high-energy electrons and positrons in the Galactic halo. PAMELA has measured a sharp rise in the positron fraction up to 80 GeV. Fermi has found a hardening of the total electronic cosmic ray spectrum above 100 GeV with a break confirmed by HESS at around 1 TeV. Excess microwaves toward the Galactic center in the WMAP data (the WMAP "haze") are consistent with hard synchrotron radiation from a population of 10-100 GeV electrons and positrons. A recently analysis of the Fermi gamma-ray sky suggests that there is a gamma-ray counterpart to the microwave haze in the Galactic Center. I will explain how dark matter annihilations, dominantly through leptonic modes, either directly or through a new light boson, can provide a consistent explanation of all of these data.

  599. Nuclear Physics & RIKEN Theory Seminar

    "Integrability of gauge theories: a tool for QCD?"

    Presented by Andrei Belitsky, Arizona State University

    Friday, April 2, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    The spin chain description of evolution equations for higher twist operators was originally discovered in QCD more than a decade ago. In recent years this framework was intensively used to test the AdS/CFT correspondence which allows one to perform calculations at strong coupling in certain gauge theories. We give an overview of these developments with a look on their potential application to QCD.

  600. RIKEN Lunch Seminar

    "Chiral and confinement transition in finite temperature QCD"

    Presented by Peter Petreczky, BNL

    Thursday, April 1, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  601. High-Energy Physics & RIKEN Theory Seminar

    "Identifying the Inert Doublet: A Mulit-Signature Strategy for a Multi-Purpose Model"

    Presented by Brooks Thomas, University of Arizona

    Wednesday, March 31, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    The Inert doublet Model (IDM) is one of the simplest possible extensions of the Standard Model, yet it is also one of the most versatile, providing a natural dark matter candidate, applications to neutrino phenomenology and the physics of electroweak-symmetry breaking, and a natural way of addressing the LEP paradox. In this talk, I discuss the prospects for detecting signatures of the IDM at the LHC, and the connection between dark-matter physics and collider phenomenology in this simple yet compelling scenario.

  602. Nuclear Physics & RIKEN Theory Seminar

    "Small-x physics with CCFM and problems to tackle at the LHC"

    Presented by Emil Avsar, Penn State

    Friday, March 26, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    "We give a review of the CCFM (Catani-Ciafaloni-Fiorani-Marchesini) approach to small-x dynamics and discuss the problems which need to addressed in order to understand the upcoming measurements from the LHC, especially in the forward region

  603. RIKEN Lunch Seminar

    "Eccentricity fluctuations and CGC"

    Presented by Yasushi Nara, Akita International University, Japan

    Thursday, March 25, 2010, 12:30 pm
    Bldg. 510, Room 2-160

    Hosted by: Anthony Baltz

  604. Joint HET/RIKEN/YITP Seminar

    "Goldstinos"

    Presented by Jesse Thaler, Stony Brook University

    Wednesday, March 24, 2010, 2:30 pm
    SUNY Stony Brook

  605. Nuclear Physics & RIKEN Theory Seminar

    "Reconstructing jets in heavy-ion collisions"

    Presented by Gregory Soyez, CERN, Switzerland

    Friday, March 12, 2010, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Kevin Dusling

    Recently, experimental collaborations at RHIC have come out with the first jet measurements in heavy-ion collisions ever. Because of the busy environment produced in these collisions, this jet reconstruction has long been thought of as unfeasible. In this talk, I will discuss the main ingredients that are used to subtract these large background contributions. I will start with a brief review of what has already been used, then concentrate on potentially new and promising techniques, attempting to improve that mandatory subtraction.

  606. High-Energy Physics & RIKEN Theory Seminar

    "Unitarity applied to hidden sector processes"

    Presented by Antonio Delgado, University of Notre Dame

    Wednesday, March 10, 2010, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Jen