# RBRC Events

RIKEN Lunch Seminar Talks and Other Information

April 2020
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1. APR

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Friday

9 am, Bluejeans: https://bnl.bluejeans.com/726276981

Friday, April 10, 2020, 9:00 am

Hosted by: Nikhil Karthik

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9 am, Webcast

Friday, April 17, 2020, 9:00 am

Hosted by: Nikhil Karthik

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1. APR

10

Friday

NT/RIKEN Seminar

"A mode by mode approach to heavy ion collision"

Presented by Eduardo Grossi, SBU

9 am, Bluejeans: https://bnl.bluejeans.com/726276981

Friday, April 10, 2020, 9:00 am

Hosted by: Nikhil Karthik

2. APR

17

Friday

Virtual NT/RIKEN seminar

"TBA"

Presented by Debasish Banerjee

9 am, Webcast

Friday, April 17, 2020, 9:00 am

Hosted by: Nikhil Karthik

3. MAY

15

Friday

NT/RIKEN Seminar

"TBA"

2 pm, Building 510, CFNS Room 2-38

Friday, May 15, 2020, 2:00 pm

Hosted by: Nikhil Karthik

4. MAY

22

Friday

NT/RIKEN Seminar

"TBA"

Presented by Shohini Bhattacharya, Temple University

2 pm, Building 510, CFNS Room 2-38

Friday, May 22, 2020, 2:00 pm

Hosted by: Nikhil Karthik

5. JUL

17

Friday

NT/RIKEN Seminar

"TBA"

Presented by Asmita Mukharjee, IIT Bombay

2 pm, Building 510, CFNS Room 2-38

Friday, July 17, 2020, 2:00 pm

Hosted by: Nikhil Karthik

1. 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

2. 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.

3. 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.

4. 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

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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

12. 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.

13. RIKEN Lunch Seminar - CANCELLED

"TBA"

Presented by Yong Zhao, Brookhaven National Laboratory

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

14. 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.

15. 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.

16. 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.

17. 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.

18. 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.

19. 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.

20. 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

21. 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.

22. 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.

23. 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

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

30. 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).

31. 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.

32. 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.

33. 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.

34. 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.

35. 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.

36. 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.

37. 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.

38. 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.

39. 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

40. 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.

41. 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.

42. 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

43. 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.

44. 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.

45. 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]

46. 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.

47. 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.

48. 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

49. 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.

50. 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.

51. 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.

52. 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

53. NT/RIKEN Seminar

"Parton distributions in Euclidean space"

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.

54. 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.

55. 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.

56. 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.

57. 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

58. 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

59. 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

60. 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

61. 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.

62. 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

63. 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.

64. 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.

65. 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.

66. 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.

67. 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.

68. 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.

69. 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.

70. 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.

71. 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.

72. 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

73. 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.

74. 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

75. 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

76. 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.

77. 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.

78. 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.

79. 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

80. 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

81. 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.

82. 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

83. 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

84. 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.

85. 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.

86. 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

87. 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.

88. 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.

89. 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.

90. 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

91. RIKEN Lunch Seminar

"Universality in Classical and Quantum Chaos"

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.

92. 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

93. 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.

94. 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

95. 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.

96. 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.

97. Nuclear Theory/RIKEN Seminar

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

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.

98. 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.

99. 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

100. 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.

101. 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.

102. 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.

103. 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

104. 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.

105. 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

106. 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.

107. 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.

108. 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.

109. 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

110. 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

111. 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.

112. 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

113. 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.

114. 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.

115. 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.

116. 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.

117. 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.

118. 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).

119. 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.

120. 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.

121. 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.

122. 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.

123. Nuclear Theory/RIKEN Seminar

Presented by Gerald Miller, University of Washington

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

Hosted by: Chun Shen

124. 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

125. 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

126. 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.

127. 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.

128. 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.

129. 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.

130. 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.

131. 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.

132. 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.

133. 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.

134. 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.

135. Nuclear Theory/RIKEN Seminar

"Factorization and phenomenology for Transverse Momentum Dependent distributions"

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.

136. 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.

137. 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.

138. 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.

139. 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.

140. 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.

141. 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.

142. 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.

143. 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

144. 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).

145. 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

146. 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.

147. 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.

148. 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

149. 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

150. 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

151. 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

152. 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.

153. 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."

154. 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.

155. 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.

156. 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.

157. 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.

158. 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.

159. 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.

160. 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.

161. 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.

162. RIKEN Lunch Seminar

"TBA"

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

Hosted by: Hiromichi Nishimura

163. 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

164. 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.

165. 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.

166. 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.

167. 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.

168. 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

169. 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

170. 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.

171. 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

172. 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.

173. 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.

174. 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.

175. 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.

176. 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.

177. 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.

178. 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.

179. 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

180. 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.

181. 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.

182. 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.

183. 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.

184. 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.

185. 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.

186. 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.

187. 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

188. 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

189. 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.

190. 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.

191. 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

192. 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

193. 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.

194. 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

195. 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.

196. 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.

197. 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.

198. 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

199. 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.

200. 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.

201. 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

202. 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.

203. 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

204. 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.

205. 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.

206. 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

207. 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

208. 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.

209. 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.

210. 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.

211. 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.

212. Nuclear Theory/RIKEN Seminar

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

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.

213. 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.

214. 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.

215. 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.

216. 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.

217. 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

218. 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.

219. 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).

220. 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.

221. 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

222. 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.

223. 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.

224. 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.

225. 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.

226. 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.

227. 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.

228. 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

229. 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.

230. 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

231. 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

232. 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.

233. 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.

234. 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.

235. 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.

236. 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.

237. 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.

238. 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.

239. 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.

240. 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 kâŠ¥. I plan to discuss this evolution equation and show how in different kinematic regimes it yields several well-known and some previously unknown results.

241. 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.

242. 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

243. 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.

244. 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

245. 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.

246. 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.

247. 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.

248. 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.

249. 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.

250. 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

251. 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.

252. 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.

253. 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

254. 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 Î·/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 Î·/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.

255. 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

256. 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.

257. 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

258. 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.

259. 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.

260. 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

261. RIKEN Lunch Seminar

"pQCD thermodynamics with massive quarks"

Presented by Thorben Graf, Institut fÃ¼r Theoretische Physik, Johann Wolfgang Goethe-UniversitÃ¤t

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.

262. 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

263. 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.

264. 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

265. 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

266. 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.

267. 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

268. 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.

269. 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.

270. 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."

271. 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

272. 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

273. 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.

274. 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.

275. 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.

276. 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

277. 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.

278. 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.

279. 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

280. 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.

281. 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.

282. 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.

283. 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.

284. 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

285. 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.

286. 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.

287. 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

288. 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

289. 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).

290. 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

291. 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.

292. HET/RIKEN seminar

"Colorless Top Partners and Naturalness"

Presented by Gustavo Burdman, IAS/University of SÃ£o Paulo

Wednesday, May 13, 2015, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: CheinYi Chen

293. 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.

294. HET / Riken Lunch Seminar

"Stealth Composite Dark Matter"

Friday, May 8, 2015, 12 pm
Building 510 Room 2-95

Hosted by: Amarjit Soni

295. 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

296. 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.

297. 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

298. Nuclear Theory/RIKEN seminar

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.

299. 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, Eâˆ¼2 GeV, we find for the first time a remarkable consistency between high energy jet quenching and bulk perfect fluidity with Î·/sâˆ¼T3/q^âˆ¼0.1 near Tc.

300. 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

301. 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

302. 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.

303. HET/RIKEN seminar

Presented by Tongyan Lin, University of Chicago

Wednesday, April 8, 2015, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Chien-Yi Chen

304. 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.

305. 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.

306. 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

307. 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.

308. 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.

309. 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

310. 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.

311. 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

312. 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

313. 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.

314. 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.

315. 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

316. 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

317. 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

318. 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

319. 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

320. 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

321. 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.

322. 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

323. 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.

324. 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

325. 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

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 $T_{eff}$.

326. 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.

327. 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.

328. 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.

329. 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.

330. 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

331. 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

332. 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 $$m_\pi L$$.

333. 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

334. 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

335. 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

336. 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.

337. 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

338. 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

339. 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

340. 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.

341. 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.

342. 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

343. 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

344. 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)

345. 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.

346. 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.

347. 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

348. 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

349. 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.

350. 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

351. 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

352. 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.

353. 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.

354. 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

355. 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.

356. 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.

357. 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.

358. 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.

359. 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

360. 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.

361. 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.

362. 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

363. 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

364. 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.

365. 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

366. 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).

367. 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.

368. 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

369. 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.

370. 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

371. 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

372. 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.

373. 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.

374. 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.

375. 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).

376. 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

377. 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.

378. 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.)

379. 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.

380. 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

381. 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

382. 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

383. 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.

384. 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

385. 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

386. 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.

387. 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

388. 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.

389. 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.

390. RIKEN Lunch Seminar

"Symmetric forward-backward correlations as seen at RHIC"

Thursday, October 13, 2011, 12:30 pm
Building 510 / Room 2-160

Hosted by: Zhongbo Kang

391. 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.

392. 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

393. 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.

394. 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

395. 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

396. 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.

397. 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.

398. 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

399. 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

400. 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.

401. 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.

402. 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

403. Nuclear Physics & RIKEN Theory Seminar

"Chiral Symmetry and meson gases: recent developments"

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. "

404. 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

405. 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

406. 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.

407. 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

408. 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.

409. 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

410. 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.

411. 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.

412. 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

413. 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

414. 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

415. Nuclear Physics & RIKEN Theory Seminar

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.

416. 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

417. 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

418. 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

419. 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

420. 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

421. 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

422. 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

423. 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

424. 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

425. 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.

426. 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

427. 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.

428. 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

429. 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.

430. 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

431. 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

432. 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

433. High-Energy Physics & RIKEN Theory Seminar

Presented by Eduardo Pontón, Columbia University

Wednesday, April 6, 2011, 3:30 pm
Small Seminar Room, Bldg. 510

Hosted by: Thomas McElmurry

TBA

434. 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.

435. 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).

436. 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.

437. 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

438. 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).

439. 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

440. 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

441. 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.

442. 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.

443. RIKEN Lunch Seminar

"TBA"

Presented by Andrej Ficnar, Columbia University

Thursday, March 10, 2011, 12:30 pm
Building 510 / Room 2-160

444. 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

445. 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.

446. 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

447. 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.

448. 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.

449. 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

450. 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

451. 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

452. 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.

453. 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

454. 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.

455. 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

456. Joint HET/RIKEN/YITP Seminar

"TBA"

Friday, January 28, 2011, 12 pm
Building 510 Room 2-160

TBA

457. Riken Lunch Seminar

"TBA"

Presented by Bjoern Schenke, BNL

Thursday, January 27, 2011, 12:30 pm
Physics Building Rom 2-160

TBA

458. 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

459. High-Energy Physics & RIKEN Theory Seminar

Presented by Jay Wacker, SLAC

Tuesday, January 11, 2011, 2 pm
Small Seminar Room, Bldg. 510

460. 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

461. High-Energy Physics & RIKEN Theory Seminar

"LHC@BNL"

Monday, January 10, 2011, 9:30 am
Large Seminar Room, Bldg. 510

462. 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.

463. 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

464. 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

465. 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

466. 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

467. 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

468. 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.

469. 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

470. 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.

471. 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

472. 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

473. 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

474. Joint HET/RIKEN/YITP Seminar

"TBA"

Presented by Walter Goldberger, Yale

Wednesday, October 20, 2010, 2 pm
Small Seminar Room, Bldg. 510

TBA

475. Nuclear Physics & RIKEN Theory Seminar

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

476. 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

477. 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

478. 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

479. 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.

480. 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.

481. 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

482. 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

483. 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

484. 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.

485. 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.

486. 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.

487. 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

488. 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."

489. 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

490. 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.

491. 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

492. 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.

493. 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.

494. 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.

495. 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

496. 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.

497. 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

498. 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.

499. 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.

500. 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

501. 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

502. 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.

503. 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.

504. 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

505. 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.

506. 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.

507. 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

508. 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

509. 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

510. 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.

511. 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

512. 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.

513. 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

514. 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.

515. 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.

516. 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

517. 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.

518. 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

519. 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

520. Joint HET/RIKEN/YITP Seminar

"Goldstinos"

Presented by Jesse Thaler, Stony Brook University

Wednesday, March 24, 2010, 2:30 pm
SUNY Stony Brook

521. 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.

522. 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: Jennifer Kile

523. Nuclear Physics & RIKEN Theory Seminar

"Insights on the q_hat problem"

Presented by Simon Caron-Huot, Institute for Advanced Study, Princeton

Friday, March 5, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

We study the energy loss by bremsstrahlung for a high-energy jet moving in the quark-gluon plasma. We describe the jet perturbatively but we make no assumption about the interaction strengths in the plasma. We propose an equation giving the radiation rate which generalizes and unify the existing treatments by Baier-Dokshitzer-Mueller-Peigne-Schiff and Zarkarov (BDMPS-Z) and by Arnold-Moore-Yaffe (AMY). Solving it numerically we can determine approximations which are valid (or not!) under RHIC conditions. This sheds light on the discrepancy regarding the extraction of the $\hat{q}$'' parameter by different groups.

524. High-Energy Physics & RIKEN Theory Seminar

"Supersymmetry without Prejudice"

Presented by Jamie Gainer, Northwestern University and Argonne National Lab

Wednesday, March 3, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

525. Nuclear Physics & RIKEN Theory Seminar

"Bulk viscosity and the applicability of viscous hydrodynamics at RHIC"

Presented by Pasi Huovinen, University of Frankfurt

Friday, February 26, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

Based on comparisons with transport models we had concluded that relativistic viscous hydrodynamics is quite applicable at RHIC. However, when bulk viscosity is included in the description, the applicability can be severely reduced. In this talk I briefly review the comparisons with kinetic theory, propose as a rule of thumb that the entropy production during the evolution has to stay below 20% for hydrodynamic description to be applicable, and show what limits this gives to bulk viscosity and/or the applicability of hydro with bulk viscosity.

526. Nuclear Physics & RIKEN Theory Seminar

"Transport and Screening in the Magnetized Neutron Star Crusts"

Presented by Sanjay Reddy, Los Alamos National Lab

Friday, February 26, 2010, 11 am
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

After a brief discussion of some generic properties of neutron star crusts and some recent observation that probe this physics, I will discuss a new mechanism by which heat is conducted in the inner crust. In strong magnetic fields, the heat carried by superfluid phonons may become important. In addition, I will show that the modification of the electron screening of the ion-ion potential at large fields can be important implications for the mechanical structure.

527. High-Energy Physics & RIKEN Theory Seminar

"Top-Quark Pair Production Beyond Next-To-Leading Order"

Presented by Andrea Ferroglia, University of Mainz

Wednesday, February 24, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

528. Joint HET/RIKEN/YITP Seminar

"Top-Quark Pair Production Beyond Next-To-Leading Order"

Presented by Andrea Ferroglia, Mainz University

Wednesday, February 24, 2010, 2 pm
Small Seminar Room, Bldg. 510

529. Nuclear Physics & RIKEN Theory Seminar

"Quark pair creation in color electric fields and effects of magnetic fields"

Presented by Naoto Tanji, The University of Tokyo, Japan

Wednesday, February 24, 2010, 11 am
Small Seminar Room, Bldg. 510

Hosted by: Keviin Dusling

The Schwinger mechanism has been studied as a mechanism of matter formation in the context of heavy-ion collisions. In this talk, I will discuss quark pair creation from a uniform color electric field focusing on its real-time dynamics. I will also show a magnetic field enhances the quark pair creation and induces chiral charge.

530. Nuclear Physics & RIKEN Theory Seminar

"Stellar Riddles"

Presented by Carlos Bertulani, Texas A&M University-Commerce

Friday, February 19, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

ABSTRACT: The most fundamental question in nature is where do we come from, or, put another way, what are we made of? At the heart of this question is the process of nucleosynthesis. I will discuss the challenges in obtaining the nuclear physics input for the Big Bang and stellar evolution. Then I will show how a new generation of theoretical developments and experiments can shed light on the complex nuclear processes that control the evolution of stars and stellar explosions

531. RIKEN Lunch Seminar/NT

"The QCD phase diagram: Results and challenges"

Presented by Jan Pawlowski, University of Heidelberg, Germany

Thursday, February 18, 2010, 12:30 pm
Physics, Bldg. 510, Rm 2-160

Hosted by: Anthony Baltz

I review the progress made in our understanding of the QCD phase diagram within an RG approach to QCD and effective QCD models. In particular this includes a discussion of the confinement-deconfinement phase transition/cross-over, the chiral phase transition/cross-over, as well as their interrelation.

532. High-Energy Physics & RIKEN Theory Seminar

"Nonuniversal Gaugino Masses, Dark Matter and the LHC"

Presented by Brent Nelson, Northeastern University

Wednesday, February 17, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

533. Joint HET/RIKEN/YITP Seminar

"NLO QCD Predictions for Vector Bosons Plus Jets at the LHC"

Presented by Lance Dixon, SLAC

Wednesday, February 10, 2010, 2:30 pm
Small Seminar Room, Bldg. 510

Hosted by: Sally Dawson

534. Nuclear Physics & RIKEN Theory Seminar

"Thermal photons from heavy ion collisions: A spectral function approach"

Presented by Ismail Zahed, SUNY Stony brook

Friday, February 5, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

We analyze the photon rates from a hadronic gas in equilibrium using chiral reduction formulas and a density expansion. The chiral reduction is carried to second order in the pion density which in principal includes all kinetic processes of the type $X\to \pi\gamma$ and $X\to \pi\pi\gamma$. The resulting rates are encoded in the form of vacuum correlation functions which are amenable to experiment. The hadronic rates computed in this work along with the known perturbative QGP rates are integrated over the space-time evolution of a hydrodynamic model tuned to hadronic observables. The resulting yields are compared to the recent photon and low mass dilepton measurements at the SPS and RHIC. Predictions for the LHC are made.

535. RIKEN Lunch Seminar

"Novel Diagrammatic Method for Computing Transport Coefficients"

Presented by Yoshimasa Hidaka, Kyoto University, Japan

Thursday, February 4, 2010, 12:30 pm
Bldg. 510, Room 2-160

Hosted by: Anthony Baltz

536. High-Energy Physics & RIKEN Theory Seminar

"Revealing Randall-Sundrum Hidden Valleys"

Presented by Jay Hubisz, Syracuse University

Wednesday, February 3, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

I discuss gauge sectors in Randall Sundrum scenarios which are hidden from the standard model through either small gauge coupling, or vanishing quantum numbers. RS gravity provides a bridge between the standard model and the hidden sector, allowing for probes of super-weakly-coupled new physics. In particular, a Peccei-Quinn axion model is described with novel low-scale interactions.

537. Joint HET/RIKEN/YITP Seminar

"N=4 SYM and the Grassmannian"

Presented by N. Arkani-Hamed, Institute for Advanced Study

Wednesday, January 27, 2010, 2:30 pm
YITP, Stony Brook

Hosted by: Sally Dawson

538. Nuclear Physics & RIKEN Theory Seminar

"Characterizing the QCD X-Matter from the Little Bang"

Presented by Jinfeng Liao, Lawrence Berkeley Natl Laboratory

Friday, January 22, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

ABSTRACT: In this talk, I will report some progresses in characterizing the hot QCD matter (call it an "X-matter") created in the heavy ion collisions, which is the only experimentally accessible example of a strongly coupled plasma in a non-Abelian gauge theory. I will mainly discuss: (1) how "perfect" this matter is as a fluid e.g. when compared with all other fluids, and in particular what is the proper measure for such a comparison. Furthermore I will also briefly discuss: (2) whether the matter's microscopic degrees of freedom are more chromo-electric or -magnetic, and how that characterization is related to QCD confinement; (3) whether the fermions in this matter are more free or more correlated or even bound; (4) what "opaque" pattern this matter has, when imaged by a highly energetic penetrating jet.

539. RIKEN Lunch/HET/NT

"EDM's & Bayrogenesis"

Presented by Ying-chuan Li, University of Wisconsin, China

Thursday, January 21, 2010, 12:30 pm
Physics Dept., Bldg. 510, Room 2-160

Hosted by: Anthony Baltz

540. High-Energy Physics & RIKEN Theory Seminar

"N=4 SYM and the Grassmannian"

Presented by Michael Endres, Columbia University

Wednesday, January 20, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Ruth Van de Water

541. Nuclear Physics & RIKEN Theory Seminar

"Some recent results at zero and finite temperature in the Gribov approach to QCD"

Presented by Daniel Zwanziger, New York University

Friday, January 15, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

I will present an introduction to the Gribov program in QCD and its implementation by a local, renormalizable action. Some recent results on long-range dynamics at zero temperature will be described. The relation of Gribov mass to Linde infrared divergences at finite-temperature and magnetic mass will be reviewed.

542. High-Energy Physics & RIKEN Theory Seminar

Presented by Kathryn Zurek, University of Michigan

Wednesday, January 6, 2010, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

543. Nuclear Physics & RIKEN Theory Seminar

"Kink crystals and chiral spirals in the Gross-Neveu phase diagram"

Presented by Gerald Dunne, University of Connecticut (Storrs)

Thursday, December 17, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Robert Pisarski

The Gross-Neveu models are 1+1 dimensional models of chiral symmetry breaking, for which the temperature/chemical potential phase diagram has recently been found analytically. There are crystalline condensate phases, with their structure being very different for the Gross-Neveu models with discrete and continuous chiral symmetry. I also discuss the relation between the Ginzburg-Landau expansion and certain integrable models.

544. High-Energy Physics & RIKEN Theory Seminar

"Making sense of non-Hermitian Hamiltonians"

Presented by Carl Bender, Washington University

Wednesday, December 16, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Sally Dawson

ABSTRACT: The average quantum physicist on the street believes that a quantum-mechanical Hamiltonian must be Dirac Hermitian (invariant under combined matrix transposition and complex conjugation) in order to guarantee that the energy eigenvalues are real and that time evolution is unitary. However, the Hamiltonian $H=p^2+ix^3$, which is obviously not Dirac Hermitian, has a real positive discrete spectrum and generates unitary time evolution, and thus it defines a fully consistent and physical quantum theory. Evidently, the axiom of Dirac Hermiticity is too restrictive. While $H=p^2+ix^3$ is not Dirac Hermitian, it is PT symmetric; that is, invariant under combined space reflection P and time reversal T. The quantum mechanics defined by a PT-symmetric Hamiltonian is a complex generalization of ordinary quantum mechanics. When quantum mechanics is extended into the complex domain, new kinds of theories having strange and remarkable properties emerge. Some of these properties have recently been verified in laboratory experiments. If one generalizes classical mechanics into the complex domain, the resulting theories have equally remarkable properties.

545. Nuclear Physics & RIKEN Theory Seminar

"Chern-Simons Term Induced Interactions in Holographic QCD"

Presented by Grigoryan Hovhannes, Argonne National Laboratory

Friday, December 11, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

ABSTRACT: We explore the physics associated with the addition of the Chern-Simons (CS) term in two holographic models, where the strongly coupled QCD appears to be dual to certain five dimensional (5D) weakly coupled gauge theory. Essentially, we work in the chiral limit of QCD with two flavors, and employ holographic correspondence to compute vertex functions and couplings that are induced by the 5D CS term. In particular, we show that the addition of the 5D CS term allows to reproduce the appropriate chiral anomaly of QCD and much more. As an instructive example, we use one of the CS term induced couplings to provide predictions for the f_1 meson photoproduction

546. High-Energy Physics & RIKEN Theory Seminar

Presented by Ethan Neil, Yale University

Wednesday, December 9, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Ruth Van de Water

547. Nuclear Physics & RIKEN Theory Seminar

"Quarkyonic Chiral Spiral"

Presented by Toru Kojo, Brookhaven National Laboratory - RBRC

Friday, December 4, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

In a cold, dense quark matter, there may exist the density region where the system has quark Fermi sea, but also remnant of confinement near the Fermi surface. Such a matter is called quarkyonic matter, which possesses a rigorous foundation in large Nc limit. We argue the chiral properties of quarkyonic matter including nonperturbative effects by gluon propagator supported by Gribov-Zwanziger's analyses. It is shown that nonperturbative self-consistent equations are reduced to its (1+1) dimensional version, 'tHooft model in finite density. We analyze reduced model by the use of non-Abelian bosonization. We found that chiral spiral emerges with locally violating chiral symmetry but restores it globally. The possible long range to quasi-long range order phase transition is also discussed.

548. High-Energy Physics & RIKEN Theory Seminar

"Distinguishing Different Types of Dark Matter at the LHC."

Presented by Devin Walker, University of California, Berkeley, LBNL

Wednesday, December 2, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

We emphasize the stabilizing symmetry for dark matter does not have to be the commonly used parity symmetry. We therefore examine the potential of the CERN Large Hadron Collider to distinguish models with parity stabilized dark matter from models in which the dark matter is stabilized by other symmetries. We begin this talk by focusing on signatures involving the decay of partners into final states with dark matter and the Standard Model particles. Later we present work distinguishing stabilization symmetries from signals involving meta-stable partners and dark matter. We show for models without a parity stabilization symmetry the reconstructed invariant mass potentially exhibits double kinematic endpoints due to appearance of one or two DM particles in the final state. For certain scenarios, these endpoints could be measured and the dark matter mass directly reconstructed. This is to be contrasted with the decay chains for parity stabilized models where only one DM candidate appears in the decay chain. We also note that certain decay chain "topologies,'' which are absent for the parity case, generates a "cusp'' in the invariant mass distribution of visible particles. Such generates a distinctive feature which is generally invariant of the various spin configurations. We demonstrate this by presenting novel reconstruction techniques. We illustrate these general ideas with explicit models.

549. Nuclear Physics & RIKEN Theory Seminar

"Baryonic susceptibilities and Critical behavior in heavy ion collisions"

Presented by Shu Lin, SUNY Stony Brook

Friday, November 20, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin dusling

abstract: In the first part of the talk, I will focus on the baryon contribution to the baryonic susceptibilities. Two types of baryons are identified: one is stringy baryons which are chirally insensitive and have a temperature dependent string tension. Its contribution shows a rise and fall near critical temperature. The other is chirally sensitive non-stringy baryons, through which the dependence on quark chemical potential enters the baryonic density of states. In the second part of the talk, I will talk about the existence of critical impact parameter in heavy ion collisions, modeled by gravitational shock wave collision. I will discuss its dependence on energy and saturation scale and comment on its connection with collision of source-free shock waves.

550. Joint HET/RIKEN/YITP Seminar

"Non-Minimal Dark Matter--Nucleon Scattering"

Presented by Aaron Pierce, University of Michigan

Wednesday, November 18, 2009, 2:30 pm
YITP, SUNY Stony Brook (Room Math 6-125)

Hosted by: Sally Dawson

551. Nuclear Physics & RIKEN Theory Seminar

"Equation of State and Phase Fluctuations near the Chiral Critical Point"

Presented by Joseph Kapusta, University of Minnesota

Friday, November 13, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

The thermodynamics and critical exponents and amplitudes of high temperature and dense matter near the chiral critical point is studied. The parameterized equation of state matches on to that calculated with lattice QCD at zero chemical potential and to the known properties of nuclear matter at zero temperature. The extent to which finite size effects wash out the phase separation near the critical point is determined. The degree to which the critical point acts as an attractor in high energy heavy ion collisions is also investigated.

552. RIKEN Lunch Seminar

"Connecting Polyakov Loops to the Thermodynamics of $SU(N_c)$"

Presented by Jorge Noronha, Columbia University, Brazil

Thursday, November 12, 2009, 12:30 pm
Room 2-220

Hosted by: Anthony Baltz

553. Nuclear Physics & RIKEN Theory Seminar

"Hydrodynamical behavior and thermalization of a strongly coupled Yang-Mills plasma from AdS/CFT"

Presented by Guillaume Beuf, Brookhaven National Laboratory

Friday, November 6, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

Some data from RHIC suggest that the QGP may be strongly coupled, and behave as a nearly perfect fluid. This observation has triggered many studies based on gauge/string duality. In particular, the hydrodynamical behavior of strongly coupled gauge theories is now undertood thanks to the fluid/gravity correspondence. The understanding of the thermalization process towards a QGP remains one of the main theoretical problems in heavy ion collisions physics. Assuming that this process occurs at strong coupling, it can be adressed using AdS/CFT. After a review of the fluid/gravity correspondence, I will present recents attempts to study thermalization with AdS/CFT. Then I will briefly discuss the problem of the choice of meaningful initial conditions before thermalization.

554. RIKEN Lunch Seminar

"Lattice simulation of a three dimensional effective theory for SU(2) Yang Mills"

Presented by Dominik Smith, University of Frankfurt, Germany

Thursday, November 5, 2009, 12:30 pm
Physics Dept., Room 2-160

Hosted by: Robert Pisarski

It is widely believed that at sufficiently high temperatures or densities, protons and neutrons dissolve into a gas of their constituents, a quark gluon plasma. However, the deconfining phase transition does not pass directly to a gas which can be described as non-interacting particles, but traverses a strongly coupled region, where perturbative methods fail. Also, the usual three dimensional effective theory, EQCD, cannot account for the fluctuations between distinct Z(N) vacua above the phase transition, because EQCD breaks the Z(N) center-symmetry explicitly. As a model for the strongly coupled quark gluon plasma (SQGP), we study an effective theory of SU(2) Wilson Lines, which is constructed in such a way that it respects all of the symmetries of four-dimensional SU(2) pure gauge theory. In this picture, the QGP is a condensate of flux tubes, rather than a gas. Lattice simulations are performed, to investigate whether a "fuzzy bag" term, which is added to the Lagrangian by hand, can induce eigenvalue repulsion and therefore generate non-perturbative fluctuations.

555. High-Energy Physics & RIKEN Theory Seminar

"Light Pseudoscalar Mesons in Lattice QCD with Staggered Quarks: Results and Issues"

Presented by Claude Bernard, Washington University, St. Louis

Wednesday, November 4, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Ruth Van de Water

556. Nuclear Physics & RIKEN Theory Seminar

"Lattice based Equation of State and its effect on the hydrodynamical evolution"

Presented by Pasi Huovinen, University of Frankfurt

Friday, October 30, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

At low temperatures the hadron resonance gas model is expected to give a fair description of thermodynamic quantities even if the lattice QCD calculation leads to significantly different result. In this talk I show that the discrepancies are significantly reduced if we take into account the larger values of quark mass, i.e. larger hadron masses, used in lattice calculations as well as the finite spacing errors. Thus, I propose thatelow the critical temperature, T_c, the physical EoS is close to the hadron resonance gas EoS, and present a parametrization interpolating consistently between hadron resonance gas EoS below and lattice EoS above T_c. In the second part of the talk I show how such an Equation of State affects the evolution of the system and compare it with old calculations done using an Equation of State with a first order phase transition.

557. RIKEN Lunch Seminar

"Neutrinos from collapsing stars and future neutrino telescopes"

Presented by Cecilia Lunardini, Arizona State Univ/RBRC

Thursday, October 29, 2009, 12:30 pm
Conference Rm 2-160, Bldg. 510

Hosted by: Anthony Baltz

558. High-Energy Physics & RIKEN Theory Seminar

"Reduction of one-loop scattering amplitudes with the OPP method"

Presented by Giovanni Ossola, New York City College of Technology

Wednesday, October 28, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

559. Nuclear Physics & RIKEN Theory Seminar

"Integrability of high energy scattering amplitudes in multi-color QCD and N=4 SUSY"

Presented by Lev Lipatov, Petersburg Nuclear Physics Institute (PNPI), Russia

Wednesday, October 28, 2009, 11 am
Small Seminar Room, Bldg. 510

Hosted by: Robert Pisarski

The BFKL aproach based on analitycity, unitarity, renormalizability and crossing symmetry of high energy scattering amplitudes is reviewed. The BKP equations in LLA for the colorless composite states of reggeized gluons in the t'Hooft limit have properties of the Moebius invariance, holomorphic separability, duality and integrability. The BDS ansatz for two gluon production amplitude in N=4 SUSY is shown to be incompatible with the Steinmann relations, which is related to the fact, that this anzatz does not take into account contributions of the Mandelstam cuts. It is shown, that the Hamiltonian for the color octet composite states of several reggeized gluons coincides with the local Hamiltonian of an integrable open Heisenberg spin chain. Analytic properties and an exponentiation hypothesis are enough to calculate production amplitudes in several orders of perturbation theory.

560. High-Energy Physics & RIKEN Theory Seminar

"Top Jets & Precision Measurements of the Top Quark Mass"

Presented by Sean Fleming, University of Arizona

Wednesday, October 21, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Jennifer Kile

561. Nuclear Physics & RIKEN Theory Seminar

"Radiative energy loss and v2 spectra for viscous hydro"

Presented by Derek Teaney, Stony Brook University

Friday, October 16, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

This work investigates the consequence of the non-equilibrium phase space distribution on spectra and elliptic flow. We show that the departure from equilibrium on the freezeout surface dominates viscous corrections to $v_2(p_T)$. However, the energy dependence of the departure from equilibrium is not known {\it a priori}. We argue that it is probably not $\propto p_T^2$ as has generally been assumed; and it is generally different for different species. Weaker $p_T$ dependence would lead to straighter $v_2(p_T)$ curves at the same value of viscosity. A species dependent equilibration rate, with baryons equilibrating faster than mesons, can explain "constituent quark scaling" without invoking coalescence models.

562. Joint HET/RIKEN/YITP Seminar

Presented by Nathan Seiberg, IAS, Princeton, New Jersey

Wednesday, October 14, 2009, 2 pm
YITP, SUNY Stony Brook (Room Math 6-125)

Hosted by: Sally Dawson

563. Nuclear Physics & RIKEN Theory Seminar

"Recombinant J/Psi production in strongly-coupled quark-gluon plasma"

Presented by Clint Young, Stony Brook University

Friday, October 9, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

The dynamics of charm quarks at the RHIC can be approximated by the Langevin equation, a stochastic differential equation which evolves the distributions towards the thermal predictions. We have extended this approach to charm quark-antiquark pairs, which also experience an attractive interaction measured with lQCD. This model has some agreement with the measured anomalous suppression of J/Psi yields in Au+Au collisions at the RHIC. We now also consider the possibility of recombinant J/Psi production in heavy-ion collisions, which may increase the J/Psi yields in some collisions significantly. We find that by considering recombinant production, we may achieve agreement with even the latest analysis of R_AA/R_CNM, where the observed suppression is quite smaller than previously thought.

564. RIKEN Lunch Seminar

"Electromagnetic Form Factors of a Nucleon in Full Lattice QCD"

Presented by Sergey Syritsyn, Massachusetts Institute of Tehnology

Thursday, October 8, 2009, 12:30 pm
Rm 2-160; Bldg. 510

Hosted by: Anthony Baltz

I will present a recent high-statistics calculation of nucleon electromagnetic form factors using lattice QCD with 2+1 flavors of dynamical domain wall quarks. This is the first calculation with (almost) chirally symmetric both sea and valence quark actions at pion masses down to m_\pi=300MeV and at lattice spacing as small as a=0.084fm. Using specially tuned techniques to suppress gauge noise and excited state contaminations, we determine the nucleon form factors with a remarkable precision. I will also present the exrapolation of our results using two-flavor chiral perturbation theory and comparison to experiment.

565. Nuclear Physics & RIKEN Theory Seminar

"Topics in the dynamics of holographic matter"

Presented by Andrei Parnachev, Stony Brook University

Friday, October 2, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Kevin Dusling

We will use methods of gauge/string duality to study properties of strongly interacting matter, including Fermi liquids. Condensed matter theorists are encouraged to attend the seminar.

566. RIKEN Lunch Seminar

"Some Recent Progress on Single Transverse Spin Asymmetry"

Presented by Zhongbo Kang, RBRC, Physics

Thursday, October 1, 2009, 12:30 pm
Room 2-160, Bldg. 510

Hosted by: Anthony Baltz

567. Nuclear Physics & RIKEN Theory Seminar

"Quantum critical transport in clean graphene"

Presented by Joerg Schmalian, Iowa State University

Friday, September 25, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

We study the role of electron-electron Coulomb interaction in clean graphene and determine the d.c. conductivity, the shear viscosity, and the diamagnetic response of this unique material. Key for an understanding of the Coulomb interaction is the fact that clean, undoped graphene is quantum critical with a marginally irrelevant "fine structure constant". Using standard crossover arguments combined with a quantum kinetic theory, we derive scaling laws, valid near this quantum critical point, that dictate the nontrivial magnetic and charge response of interacting graphene. The most dramatic consequence of this analysis is the anomalous collision-dominated, hydrodynamic transport: the d.c. conductivity of clean graphene is shown to diverge for decreasing temperature (as the square of the logarithm of T), making this material a quantum critical metal. The shear viscosity vanishes as the temperature goes to zero, with an viscosity - entropy density ratio that is close to the behavior expected for a perfect fluid. Finally we show that the viscosity - entropy density ratio is further reduced at the chiral symmetry breaking transition between metallic and insulating behavior.

568. RIKEN Lunch Seminar

"Extreme limits of QCD: On QCD with many flavors or many colors"

Presented by Jens Braun, TRIUMF, Germany

Thursday, September 24, 2009, 12:30 pm
Conference Rm 2-160, Physics, Bldg. 510

Hosted by: Anthony Baltz

569. Joint HET/RIKEN/YITP Seminar

"Fourth Generation and Electroweak Symmetry Breaking"

Presented by Gustave Burdman, Sao Paulo/FNAL

Wednesday, September 23, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Sally Dawson

570. High-Energy Physics & RIKEN Theory Seminar

"Probing B/L Violation in the Extended Scalar Models at the LHC"

Presented by Kai Wang, University of Tokyo

Wednesday, September 16, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

571. Nuclear Physics & RIKEN Theory Seminar

"Systematics of High Temperature Perturbation Theory"

Presented by Emil Mottola, Los Alamos National Laboratory

Thursday, August 27, 2009, 12:30 pm
Room 2-160, Bldg. 510

Hosted by: Gregory Soyez

The systematics and reorganization of the perturbative loop expansion in high temperature gauge theories is investigated. In addition to infrared divergences in the bare loop expansion with massless fermions, further evidence for the necessity of a systematic restructuring of perturbation theory comes from the explicit gauge parameter dependence of the fermion damping rate at both one and two-loops. The calculation of the two-loop fermion self-energy in QED shows that the leading terms in the high temperature expansion arise from an explicit hard-soft factorization pattern, in which one of the loop integrals is hard (p ~ T), nested inside a second loop integral which is soft (p ~ eT). There are no hard-hard contributions to the two-loop self-energy at leading order at high T. This hard-soft factorization pattern is necessary for the resummation over multiple loops to coincide with the one-loop self-energy calculated with HTL dressed propagators and vertices, and to yield the complete next-to-leading order correction to the self-energy at scales ~eT, which is both infrared finite and gauge invariant. The gauge invariant effective action corresponding to this resummation and possible extensions of the resummation program to softer processes not captured in the HTL approach will also be discussed.

572. Nuclear Physics & RIKEN Theory Seminar

Presented by Edmond Iancu, Saclay, France

Friday, August 21, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

After briefly recalling the experimental results at RHIC which support the picture of a strongly-coupled, deconfined QCD matter, I discuss applications of the string theory, via the AdS/CFT correspondence, to the study of such a form of matter. I emphasize some striking consequences of the strong-coupling scenario, like the absence of jets, the strong suppression of the parton distributions at large values of Bjorken-x, and a novel mechanism (the medium-induced parton branching) for the energy loss and the momentum broadening of a hard probe. I discuss a recent proposal for a lattice measurement which should clarify whether the quark-gluon plasma is effectively strongly-coupled or not in the temperature range of interest for RHIC and LHC.

573. Nuclear Physics & RIKEN Theory Seminar

"Searching for a mean string theory description of the pure gauge theory in the IR"

Presented by Oleg Andreev, TU Munich and Landau Moscow

Monday, August 17, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

574. Nuclear Physics & RIKEN Theory Seminar

"Cold Relativistic Superfluids: Transport Phenomena and Applications"

Presented by Cristina Manuel, Instituto de Ciencias del Espacio (CSIC)

Friday, August 14, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

Superfluidity occurs in cold systems after the appearance of a quantum condensate that breaks spontaneously a global U(1) symmetry. We review the basic features of relativistic superfluid hydrodynamics, paying special attention to color-flavor locked quark matter. At very low temperatures, transport phenomena is dominated by the contribution of the superfluid phonon, a Goldstone mode of the system. Using low energy effective field theory techniques, one can estimate relaxation time scales and the four viscosity coefficients of the superfluid. We also show how to construct a transport equation for the phonon using a gravity analogue model. Finally, we discuss how the knowledge of all the dissipative processes is needed in astrophysical scenarios for the study of rotational properties of compact stars

575. High-Energy Physics & RIKEN Theory Seminar

"Flavor Physics with Friedberg-Lee hidden symmetries & the case for the Standard Model with 4 families"

Presented by Shaouly Bar-Shalom, Technion, Haifa

Wednesday, August 12, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

576. High-Energy Physics & RIKEN Theory Seminar

"MSSM Higgs extensions: a model-independent approach"

Presented by Eduardo Ponton, Columbia University

Wednesday, August 5, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

577. High-Energy Physics & RIKEN Theory Seminar

"Anti-Matter Signals from Matter Stability (DM from RS-GUT @ Galactic Cosmic Rays and LHC)"

Presented by Seung J. Lee, Weizmann Institute of Science

Wednesday, July 22, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

578. Nuclear Physics & RIKEN Theory Seminar

Presented by Anastasios Taliotis, Ohio State University

Friday, July 17, 2009, 11 am
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

We calculate the total cross section for deep inelastic scattering (DIS) on a nucleus at high energy for a strongly coupled N = 4 super Yang-Mills theory using AdS/CFT correspondence. In analogy to the small coupling case we argue that at high energy the total DIS cross section is related to the expectation value of the Wilson loop formed by the quark-antiquark dipole. We model the nucleus by a metric of a shock wave in AdS5. We then calculate the expectation value of the Wilson loop by finding the extrema of the Nambu-Goto action for an open string attached to the quark and antiquark lines of the loop in the background of an AdS5 shock wave. We find three extrema of the Nambu-Goto action: the string coordinates at the extrema are complex-valued and are given by three different branches of the solution of a cubic equation. The physically meaningful solutions for the total DIS cross section are given either by the only branch with a purely imaginary string coordinate in the bulk or by a superposition of the two other branches. For both solutions we obtain the forward scattering amplitude N for the quark dipole-nucleus scattering. We study the onset of unitarity with increasing center-of-mass energy and transverse size of the dipole: we observe that for both solutions the saturation scale, while energy-dependent at lower energies, at very high energy becomes independent of energy/Bjorken-x. The saturation scale depends very strongly on the atomic number of the nucleus as Qs ~ A^1/3.

579. High-Energy Physics & RIKEN Theory Seminar

"Colored Scalars at the LHC"

Presented by Thomas McElmurry, University of Wisconsin - Madison

Wednesday, July 8, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

580. High-Energy Physics & RIKEN Theory Seminar

"The inside and outside of top jets"

Presented by Gilad Perez, Weizmann Institute of Science, Israel

Tuesday, July 7, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

581. Nuclear Physics & RIKEN Theory Seminar

"Small-x Evolution of Structure Functions in the Next-to-Leading Order"

Presented by Giovanni Chirilli, Old Dominion University/Jefferson Lab

Friday, June 26, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

The high-energy behavior of amplitudes in gauge theories can be reformulated in terms of the evolution of Wilson-line operators. In the leading order this evolution is governed by the non-linear Balitsky-Kovchegov (BK) equation. The NLO corrections define the scale of the running-coupling constant in the BK equation and in QCD, its kernel has both conformal and non-conformal parts. To separate the conformally invariant effects from the running-coupling effects, we calculate the NLO evolution of the color dipoles in the conformal N = 4 SYM theory, then we define the "composite dipole operator" with the rapidity cutoff preserving conformal invariance, and the resulting Mobius invariant kernel for this operator agrees with the forward NLO BFKL calculation. In QCD, the NLO kernel for the composite operators resolves in a sum of the conformal part and the running-coupling part.

582. High-Energy Physics & RIKEN Theory Seminar

"Moments of the 3-loop corrections to the heavy flavor contribution to F_2(x,Q^2) for Q^2 >> m^2"

Presented by Sebastian Klein, DESY

Wednesday, June 24, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

583. Nuclear Physics & RIKEN Theory Seminar

"On heavy meson dissociation in QCD matter: a comparison of Debye screening and multiple scattering"

Presented by Bin Wu, Peking University

Friday, June 19, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

In this talk, I will report what we find about the criterion for fast moving heavy mesons in an infinite hot quark-gluon plasma by comparing Debye screening and multiple scattering. And I will also talk about the dissociation of mesons due to multiple scattering in cold and hot QCD matter.

584. High-Energy Physics & RIKEN Theory Seminar

"Academic Lectures: Top Quark Physics, #1"

Presented by Tim Tait, Argonne National Laboratory

Wednesday, June 17, 2009, 2 pm
Large Seminar Room, Bldg. 510

Hosted by: Sally Dawson

585. Nuclear Physics & RIKEN Theory Seminar

"Jet evolution in stable and unstable non-Abelian plasmas"

Presented by Bjoern Schenke, McGill University, Canada

Friday, June 12, 2009, 1 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

I present results for elastic energy loss and momentum broadening of high momentum partons in hot and dense non-Abelian plasmas, obtained by solving the coupled system of Wong-Yang-Mills equations on a lattice in real time. Including hard elastic collisions among the particles we find cutoff independent results for collisional energy loss and momentum broadening in stable plasmas. Furthermore, I present the effects of instabilities on jet-broadening in anisotropic plasmas. In this case the partons experience asymmetric broadening in the extended domains of growing color fields.

586. Nuclear Physics & RIKEN Theory Seminar

"The story behind a half - from current probes to future avenues"

Presented by Marco Stratmann, Wurzburg/Regensburg University, Germany

Monday, June 8, 2009, 1 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

587. Nuclear Physics & RIKEN Theory Seminar

Presented by Nasser Demir, Duke University

Friday, June 5, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

Ultrarelativistic heavy-ion collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) are thought to have produced a state of matter called the quark-gluon plasma, characterized by a very small shear-viscosity to entropy-density ratio eta/s, near the lower bound predicted for that quantity by the KSS bound. As the produced matter expands and cools, it evolves through a phase described by a hadron gas with rapidly increasing eta/s. We present a calculation of eta/s as a function of temperature utilizing the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model, and investigate the effect of the separation of thermal vs chemical freezeout on eta/s in our calculation. Our results find that eta/s in the hadronic phase is rather large, and the oft-discussed viscous hydrodynamics calculations suggest a strong temperature dependence of eta/s, especially as it crosses T_c in a heavy ion reaction.

588. High-Energy Physics & RIKEN Theory Seminar

Presented by Matthew Reece, Princeton Center for Theoretical Science

Wednesday, May 20, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

589. Nuclear Physics & RIKEN Theory Seminar

"Asymptotic Freedom in Yang-Mills Gauge Theory from Open String Loops"

Presented by Charles Thorn, University of Florida

Friday, May 8, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

590. Joint HET/RIKEN/YITP Seminar

"Implications of the Higgs Discovery in MSSM"

Presented by Ian Low, Argonne National Laboratory/Northwestern University

Wednesday, May 6, 2009, 2:30 pm
YITP, SUNY Stony Brook (Room Math 6-125)

Hosted by: Hooman Davoudiasl

591. Nuclear Physics & RIKEN Theory Seminar

"Spin - How much do we know?"

Presented by Jianwei Qiu, Department of Physics and Astronomy, Iowa State University

Friday, May 1, 2009, 3:30 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

Protons and neutrons have spin 1/2 and are known to be the building blocks of matter. They are the bound states of quarks and gluons, whose dynamics is best described by Quantum Chromodynamics (QCD). I will briefly review how to express the proton spin in terms of the degrees of freedom of quarks and gluons. It is a challenge to directly measure individual contribution of quarks and gluons to the proton spin. I will show that high energy collisions with measured polarization offer many new opportunities to probe QCD dynamics that could not be reached by spin-averaged collisions. A successful spin program could shed the light on how QCD encompasses both protons and neutrons and the quark and gluon degrees of freedom that make them up.

592. High-Energy Physics & RIKEN Theory Seminar

"Electromagnetic Neutral-Meson Decays on the Lattice"

Presented by Saul Cohen, Jefferson Lab

Wednesday, April 29, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Taku Izubuchi

I present a study of two-photon decays of light mesons, focusing on the neutral pion decay. This important process highlights the effects of the axial anomaly in QCD but has been little studied on the lattice. By applying the Lehmann-Symanzik-Zimmermann (LSZ) reduction formula, we reconstruct the electromagnetic matrix elements from three- point vector-vector Green functions calculated on full-QCD lattices.

593. Nuclear Physics & RIKEN Theory Seminar

"Magnetic Moment of the Delta and Omega baryons on the lattice"

Presented by Christopher Aubin, College of William & Mary

Friday, April 17, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Taku Izubuchi

I will discuss a lattice calculation of the magnetic moments of the Delta and Omega baryons using a background electromagnetic field technique with 2+1 flavors of anisotropic Clover fermions, on lattices generated by the Hadron Spectrum Collaboration. I will go into some detail of the systematics associated with using background EM fields on the lattice, as well as issues in extending the method to calculate higher moments.

594. Joint HET/RIKEN/YITP Seminar

"Constraining Interactions in Cosmology's Dark Sector"

Presented by Mark Trodden, University of Pennsylvania

Wednesday, April 15, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Hooman Davoudiasl

595. High-Energy Physics & RIKEN Theory Seminar

"Nearly Conformal Gauge Theories and Compositeness at the LHC"

Presented by Julius Kuti, University of California, San Diego

Wednesday, April 8, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Taku Izubuchi

I will review recent progress on the nonperturbative studies of nearly conformal gauge theories which provide a mechanism to replace the conventional Higgs sector of the standard model. The conformal window is identified in these theories in different flavor and color representations by establishing the chirally broken phase and the fixed point of the running gauge coupling. Reliable results are beginning to emerge from lattice calculations by matching to low energy Goldstone dynamics and random matrix theory. The running coupling is determined from the renormalization behavior of Wilson loops and from the Schrodinger functional. The challenges and difficulties of the calculations, unlike the ones in QCD, will be reviewed as well.

596. Nuclear Physics & RIKEN Theory Seminar

"QCD and the Hagedorn Spectrum"

Presented by Thomas Cohen, University of Maryland

Friday, April 3, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

597. Joint HET/RIKEN/YITP Seminar

"Fundamental Physics from the Sky"

Presented by Stefano Profumo, SCIPP, University of California, Santa Cruz

Wednesday, April 1, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Hooman Davoudiasl

Can we learn about New Physics with astronomical and astro-particle data? Understanding how this is possible is key to unraveling one of the most pressing mysteries at the interface of cosmology and particle physics: the fundamental nature of dark matter. Rapid progress may be within grasp in the context of an approach which combines information from high-energy particle physics with cosmic-ray and traditional astronomical data. I discuss recent puzzling data on cosmic-ray electrons and positrons and their interpretation. I show how the Fermi Space Telescope will soon shed light on those data as well as potentially on several dark matter particle properties. I then introduce a novel approach to particle dark matter searches based on the complementarity of astronomical observations across the electromagnetic spectrum, from radio to X-ray and to gamma-ray frequencies.

598. Nuclear Physics & RIKEN Theory Seminar

"On the behavior of large-N QCD with nonzero chemical potentials"

Presented by Barak Bringoltz, University of Washington

Friday, March 27, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

I will discuss the way QCD behaves at zero temperature and nonzero density in its large-N limit. I will first present, and resolve, certain subtle confusions in the literature and show that while quarks are not back-reacting on the gauge fields at large-N, they are certainly not "quenched" in any sense. I will then describe a recent calculation in which the large-N ground state of two-dimensional QCD was found for arbitrary values of the baryon number, volume, quark mass and lattice spacing. I will discuss the resulting phase diagram that contains a helical crystal of baryons. If time allows I will remark on the implications of this phase diagram on the validity of lattice studies that rely on "Eguchi-Kawai" volume independence, and on the properties of the QCD "sign problem".

599. Nuclear Physics & RIKEN Theory Seminar

"Formation of horizon and equilibration of QGP"

Presented by Shu Lin, Stony Brook University

Friday, March 20, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

I will start with a short review on various probes to Quark Gluon Plasma studied by AdS/CFT. The study of the probe typically amounts to solving linearized Einstein equation. The more challenging task is to understand the equilibration of matter and formation of QGP. I will talk about a specific gravitational collapse model, which is dual to the thermalization of gauge field on the boundary. We found the spectral density of stress energy tensor differs from its thermal counterpart by some general oscillation. I will also talk about the recent works on entropy estimation in heavy ion collision from gravitational shock wave collision. We found the existence of critical impact parameter, beyond which no horizon can form. In the dual field theory, it means matter produced in the collision cannot thermalize.

600. Nuclear Physics & RIKEN Theory Seminar

"Universality in Early Flow at RHIC"

Presented by Joshua Vredevoogd, Michigan State University

Friday, March 13, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

It was long thought that early thermalization of the hot matter created in high energy heavy ion collisions was required to simultaneously explain the large elliptic flow and the source sizes. We will show instead that for any description of the matter with a traceless stress-energy tensor - fields or particles, equilibrated or not - early flow is generated at the same level. This significantly lessens the uncertainty in modeling the early stages of the collision.

601. High-Energy Physics & RIKEN Theory Seminar

"Electroweak precision physics with W and Z bosons"

Presented by Doreen Wackeroth, SUNY at Buffalo

Wednesday, March 11, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

The production of W and Z bosons is one of the best understood and most precisely studied processes. However, in view of the increased experimental precision at the Tevatron and the LHC, the available calculations and tools that provide predictions for W and Z boson observables may not be sufficient. I will give an overview of the theory status and recent developments with special emphasis on the treatment of higher-order corrections.

602. Nuclear Physics & RIKEN Theory Seminar

"Saturation and Confinement: Pomeron, Odderon, and AdS/CFT"

Presented by Chung-I Tan, Brown University

Friday, March 6, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Dima Kharzeev

In 1/Nc expansion, analyticity and crossing lead to crossing even and odd (C = ±1) vacuum exchanges at high-energy, the Pomeron and the Odderon. We discuss how, using String/Gauge duality, these can be identified with the closed string Reggeized graviton and the anti-symmetric Kalb-Ramond fields in AdS background. With confinement, these Regge singularities interpolate with glueball states. We also discuss unitarization and saturation based on eikonal sum in AdS.

603. High-Energy Physics & RIKEN Theory Seminar

"The Lee-Wick Standard Model"

Presented by Donal O'Connell, Institute for Advanced Studies, Princeton

Wednesday, March 4, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

604. Nuclear Physics & RIKEN Theory Seminar

"The Response of a Thermal QGP to Radiating Hard Partons"

Presented by Bryon Neufeld, Duke University

Friday, February 27, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

I calculate the total energy deposited into the medium per unit length by fast partons traversing a quark-gluon plasma. The medium excitation due to collisions is taken to be given by the well known expression for the collisional drag force. The radiative energy loss of the parton contributes to the energy deposition because each radiated gluon acts as an additional source of collisional energy loss in the medium. I derive a differential equation which governs how the spectrum of radiated gluons is modified when this energy loss is taken into account. This modified spectrum is then used to calculate the differential energy loss due to the interactions of radiated gluons with the medium. The final result for the energy deposited into the medium per unit length, which is a sum of the primary and the secondary contributions, is then treated as the coefficient of a local hydrodynamic source term. Numerical results are presented for the medium response for the case of two fast, back-to-back partons created in an initial hard interaction.

605. Joint HET/RIKEN/YITP Seminar

"Dark Matter Sees the Light"

Presented by Michele Papucci, IAS, Princeton

Wednesday, February 25, 2009, 2:30 pm
YITP, SUNY Stony Brook (Room Math 6-125)

Hosted by: Hooman Davoudiasl

606. Nuclear Physics & RIKEN Theory Seminar

"How viscosity affects quarkonium states in the QGP"

Presented by Adrian Dumitru, Baruch College

Friday, February 20, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

In an expanding plasma, non-zero shear viscosity implies an anisotropic momentum distribution of particles in a fluid cell. This leads to anisotropic screening of static electric fields. I present a simple model for the static potential between infinitely heavy fundamental charges which includes the Coulomb as well as the string force and is easily extended to anisotropic plasmas. Finally, I show the binding energies of 1S/1P charmonium and bottomonium states and the polarization of 1P bb_bar states in the deconfined phase obtained from this potential.

607. Nuclear Physics & RIKEN Theory Seminar

"LHC searches: what role for QCD"

Presented by Gavin Salam, University of Paris VI, France

Friday, February 13, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

This talk considers some of the ways in which QCD might play a role in searches for new physics at the LHC. It examines the question of the reliable estimation of backgrounds, as well as that of how QCD can guide us in designing better tools to extract any new physics signals from the background.

608. Nuclear Physics & RIKEN Theory Seminar

"Quarkonia in Medium and in Heavy-Ion Collisions"

Presented by Ralf Friedrich Rapp, Texas A&M University

Friday, February 6, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

The properties of quarkonia in equilibrium QCD matter are studied and put into context with observables in ultrarelativistic heavy-ion collisions at SPS, RHIC and LHC. In the first part of the talk we focus on applications of potential models utilizing input from heavy-quark free energies computed in lattice-QCD. Applications to Euclidean correlation functions (independently computed in lattice QCD) currently exhibit a degeneracy of scenarios with small and large J/psi dissociation temperatures, due to an interplay of in-medium binding energies and heavy-quark masses. We also elaborate on the impact of color screening on quarkonium dissociation mechanisms in the Quark-GLuon Plasma. In the second part of the talk we address the current status of the phenomenology at SPS and RHIC, in particular the competition between dissociation and regeneration mechanisms and which observables might be most promising for discriminating them (including the LHC).

609. High-Energy Physics & RIKEN Theory Seminar

"Reweighting towards the chiral limit of Lattice QCD"

Presented by Anna Hasenfratz, University of Colorado

Wednesday, February 4, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Taku Izubuchi

610. Joint HET/RIKEN/YITP Seminar

Presented by Ruth Britto, Saclay, SPhT & Fermilab

Wednesday, January 28, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Hooman Davoudiasl

611. High-Energy Physics & RIKEN Theory Seminar

"Multijet Resonances at the Tevatron and the LHC"

Presented by Can Kilic, John Hopkins University

Wednesday, January 21, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

612. Nuclear Physics & RIKEN Theory Seminar

"Solitonic ground states in (color-) superconductivity"

Presented by Dominik Nickel, MIT

Tuesday, January 20, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Robert Pisarski

Inhomogeneous ground states due to imbalanced Fermi surfaces have been discussed in various contexts. The investigation of these so-called LOFF states has usually been constrained to simple ansaetze or the Ginzburg-Landau approximation. By the example of an NJL-type model I discuss new features when going beyond the Ginzburg-Landau approximation, in particular the emergence of a soliton lattice. Concentrating on one-dimensional periodic structures in 3+1 dimensions I present properties of the ground state and contrast them with known results. I also give an account on the weak-coupling limit.

613. Nuclear Physics & RIKEN Theory Seminar

"A theory of jet shapes and cross sections: from hadrons to nuclei"

Presented by Ivan Vitev, Los Alamos National Laboratory

Friday, January 16, 2009, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

For jets, with great power comes great opportunity. The unprecedented center of mass energies available at the LHC open new windows on the QGP: we demonstrate that jet shape and jet cross section measurements become feasible as a new, differential and accurate test of the underlying QCD theory. We present a first step in understanding these shapes and cross sections in heavy ion reactions. Our approach allows for detailed simulations of the experimental acceptance/cuts that help isolate jets in such high-multiplicity environment. It is demonstrated for the first time that the pattern of stimulated gluon emission can be correlated with a variable quenching of the jet rates and provide an approximately model- independent approach to determining the characteristics of the medium-induced bremsstrahlung spectrum. Surprisingly, in realistic simulations of parton propagation through the QGP we find a minimal increase in the mean jet radius even for large jet attenuation. Jet broadening is manifest in the tails of the energy distribution away from the jet axis and its quantification requires high statistics measurements that will be possible at the LHC.

614. Nuclear Physics & RIKEN Theory Seminar

"Are GPDs and TMDs related?"

Presented by Marc Schlegel, Jefferson Lab

Friday, December 19, 2008, 11 am
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

Generalized Parton Distributions (GPDs) and Transverse Momentum Dependent Parton Distributions (TMDs) are a priori different classes of parton distributions. While GPDs appear in the description of hard exclusive processes, TMDs are important for semi-inclusive processes like Drell-Yan or semi-inclusive DIS. Nevertheless, non-trivial relations between GPDs and TMDs have been suggested recently. In this talk the status of these relations are discussed and some new ideas on this matter are presented.

615. High-Energy Physics & RIKEN Theory Seminar

"Lattice determination of B0- B0 bar mixing parameters in the Standard Model and beyond"

Presented by Elvira Gamiz, University of Illinois

Wednesday, December 17, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Taku Izubuchi

616. Nuclear Physics & RIKEN Theory Seminar

"The role of monopoles in a gluon plasma"

Presented by Claudia Ratti, Stony Brook University

Friday, December 12, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

We study the role of magnetic monopoles at high enough temperature $T>2T_c$, when they can be considered heavy, rare objects embedded into matter consisting mostly of the usual "electric" quasiparticles, quarks and gluons. We find that, while this process hardly influences thermodynamic quantities, it produces a large transport cross section, keeping viscosity small enough for hydrodynamics to work at LHC.

617. Joint HET/RIKEN/YITP Seminar

"The Planck Scale from Top Condensation"

Presented by Eduardo Ponton, Columbia University

Wednesday, December 10, 2008, 2:30 pm
YITP, SUNY Stony Brook (Room Math 6-125)

Hosted by: Hooman Davoudiasl

618. Nuclear Physics & RIKEN Theory Seminar

"From Quarks and Gluons to Hadrons: A Study of the QCD Phase Boundary"

Presented by Jens Braun, TRIUMF Canada

Friday, December 5, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

I discuss chiral symmetry breaking in QCD with its underlying mechanisms in terms of quarks and gluons and show the chiral phase boundary in the plane of temperature and number of (massless) quark flavors obtained from a functional renormalization group approach. Moreover, the dependence of the phase transition temperature on the quark chemical potential is discussed. The subject of the last part of the talk is the deconfinement phase transition in Yang-Mills theory. The results obtained from a functional renormalization group approach for the order-parameter potential, namely the Polyakov-loop potential, are shown.

619. High-Energy Physics & RIKEN Theory Seminar

"Emergent Electroweak Gravity"

Presented by Robert McElrath, CERN

Wednesday, December 3, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

620. Nuclear Physics & RIKEN Theory Seminar

"Bulk, shear and heavy ion collisions"

Presented by Pasi Huovinen, Purdue University

Friday, November 21, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

In this talk I will concentrate on entropy production in heavy ion collisions due to shear and bulk viscosities. I will review the basics of causal viscous hydrodynamics and estimate the validity of the hydrodynamical description by comparing with transport theory calculations and by estimating the amount of produced entropy. I will also assess the relative contributions of shear and bulk viscosities to the evolution.

621. Joint HET/RIKEN/YITP Seminar

"From Vortices in Superconductivity to Quark Confinement"

Presented by Mikhail Shifman, University of Minnesota

Wednesday, November 19, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Hooman Davoudiasl

Supersymmetry, born in the early 1970s, is a very rich theory which is supposed to describe the widest range of natural phenomena. Although it has not yet been discovered experimentally, it proved to be a powerful tool in Quantum Chromodynamics (QCD) -- the theory of hadrons -- and strongly coupled gauge theories at large. Efforts aimed at solving various aspects of QCD basing on supersymmetry and string-inspired ideas bring fruits. In a remarkable entanglement, theoretical constructions of the 1970s and 1990s combine with today's ideas to provide new insights and a deeper understanding.

622. Nuclear Physics & RIKEN Theory Seminar

"High-Energy Gluon Bremsstrahlung in a Finite, Expanding Medium"

Presented by Peter Arnold, University of Virginia

Friday, November 14, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

High-energy gluon bremsstrahlung in a QCD plasma is suppressed by the Landau-Pomeranchuk-Migdal (LPM) effect. At very high energies E, various folks have analyzed the problem analytically in the limit that log(E) is treated as large. In this talk, I will give a qualitative discussion of the LPM effect and the equations which describe it. Then I will present new results that magically simplify previous formulas derived for the bremsstrahlung gluon emission spectrum in the large log(E) limit. I will also discuss the interplay between two different approximations that have been used to study energy loss in the large log(E) limit, known as the "harmonic oscillator" approximation and the opacity expansion.

623. Nuclear Physics & RIKEN Theory Seminar

"Some cosmological LHC and other physics aspects of new heavy colored particles carrying an extra color' with 10 eV -10 KeV scale"

Presented by Prof. Shmuel Nussinov, Tel Aviv University

Thursday, November 13, 2008, 12:30 pm
Room 2-160, Bldg. 510

Hosted by: Gregory Soyez

624. High-Energy Physics & RIKEN Theory Seminar

"Low-scale gaugino mediation"

Presented by Witold Skiba, Yale University

Wednesday, November 12, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

625. Nuclear Physics & RIKEN Theory Seminar

"Noise and quarkonia transport in AdS5"

Presented by Derek Teaney, Stony Brook University

Friday, October 31, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

I first compute the drag and diffusion rates of heavy mesons in AdS_5. Subsequently I show how thermal noise arises in the context of gauge gravity duality. I use this identification to recompute several results previously found in the diffusion of heavy quarks. However, I extend these results to compute the photon emission rate from a fast quark in AdS_5 and contrast this rate with perturbation theory. Finally I conclude by indicating how an appealing picture of thermal noise which arises can be used to calculate the diffusion of mesons whose mass is of order the temperature.

626. High-Energy Physics & RIKEN Theory Seminar

"General Gauge Mediation"

Wednesday, October 29, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Christian Sturm

627. Joint HET/RIKEN/YITP Seminar

"Landscape Naturalness"

Presented by Scott Thomas, Rutgers University

Wednesday, October 22, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Hooman Davoudiasl

628. High-Energy Physics & RIKEN Theory Seminar

"Lattice QCD and Chiral Perturbation Theory"

Presented by Chris Sachrajda, University of Southampton/Columbia

Wednesday, October 15, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

629. Nuclear Physics & RIKEN Theory Seminar

"Non-Mach Conical Di-jet Correlations in AdS/CFT"

Presented by Jorge Noronha, Columbia University

Friday, October 10, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Gregory Soyez

The reported observation of Mach cone-like correlations between tagged (near side) jets fragments and away side associated moderate pT < 4 GeV/c hadrons has generated a lot of interest because it may provide further evidence for fast relaxation times and the near perfect fluid property of the strongly Quark-Gluon Plasma (sQGP) produced in Au+Au reactions at RHIC. In this talk, we show that far zone Mach and Diffusion wake holograms'' produced by supersonic strings in AdS/CFT do not lead to observable conical angular correlations in the strict $N_c\to\infty$ supergravity limit if Cooper-Frye hadronization is assumed. However, a special nonequilibrium Neck'' zone close to the heavy quark is shown to give rise to an apparent sonic boom azimuthal angle distribution that however does not obey Mach's law. The observation of non-Mach conical correlations associated with tagged heavy quark jets would provide additional support for novel nonperturbative dynamics as suggested by the AdS/CFT string phenomenology.

630. Joint HET/RIKEN/YITP Seminar

"Generalized unitarity and one-loop calculations"

Presented by Kirill Melnikov, Johns Hopkins University

Wednesday, October 1, 2008, 2:30 pm
YITP, SUNY Stony Brook (Room Math 6-125)

Hosted by: Hooman Davoudiasl

631. Nuclear Physics & RIKEN Theory Seminar

"Target mass corrections and beyond"

Presented by Alberto Accardi, Jefferson Lab

Friday, September 26, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Harmen Warringa

I will examine the uncertainty of perturbative QCD factorization for hadron structure functions in deep inelastic scattering at a large value of the Bjorken variable xB. The focus will be on Target Mass Corrections (TMC) and Jet Mass Corrections (JMC) in the framework of collinear factorization. The proposed corrections are needed in QCD global fits of parton distribution functions at large-x, low-Q^2 for enlarging the data set and improving the accuracy. This is especially true for polarized targets, where the bulk of the data lies in such a region of phase space. I will discuss some preliminary results including TMC for unpolarized structure functions.

632. Nuclear Physics & RIKEN Theory Seminar

"Issues about partonic transverse momentum distributions"

Presented by Alessandro Bacchetta, Jefferson Lab

Friday, September 19, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Harmen Warringa

Partonic transverse momentum distributions (TMDs) expose new aspects of the structure of the nucleon, not accessible by collinear parton distribution functions. They can be measured in semi-inclusive hard scattering experiments and require the extension of the theoretical ideas usually employed to collinear distribution functions. I will review some topics relevant for the theory and phenomenology of TMDs, focusing on a few crucial examples.

633. High Energy/Nuclear Theory/RIKEN Seminar

"Aspects of Strongly Coupled Yang-Mills Theory in 2+1 Dimensions"

Presented by Abhishek Agarwal, Max Planck Institute for Gravitational Physics Potsdam, Germany

Wednesday, September 17, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Anthony Baltz

634. Nuclear Physics & RIKEN Theory Seminar

"First results from full jet-reconstruction in heavy-ion collisions at RHIC"

Presented by Joern Putschke, Yale University

Friday, September 5, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Harmen Warringa

Measurements of inclusive hadron suppression and di-hadron azimuthal correlations in ultra-relativistic nuclear collisions have provided important insights into jet quenching in hot QCD matter, but are limited in their sensitivity due to well-known biases. Complete jet reconstruction in heavy-ion collisions would provide a direct measurement of the energy of the scattered parton before energy loss, alleviating such biases and allowing a measurement of the energy loss probability distribution necessary to extract properties of the medium in a model-independent way from hard probes. In this talk the first measurement of the inclusive jet spectrum and the fragmentation function of fully reconstructed jets in 200 GeV heavy ion collisions will be presented. The fragmentation function as well as the jet spectra in heavy ion collisions will be presented and discussed with respect to p+p reference measurements.

635. Joint HET/RIKEN Theory Seminar

Presented by Kaustubh Agashe, University of Maryland

Wednesday, August 27, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

636. Nuclear Physics & RIKEN Theory Seminar

"Optimising jet finding in pp and AA collisions"

Presented by Gregory Soyez, Brookhaven National Laboratory

Friday, August 15, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Harmen Warringa

After a generic introduction covering the recent important developments in jet physics and the need to use infrared-and-collinear-safe tools for future analysis, I will try to answer the question "what is the optimal jet algorithm for hadronic collisions?". I will show that this varies from process to process and from scale to scale, suggesting flexibility for LHC studies. Then, still in the context of finding an optimal jet finder, I will discuss practical methods to subtract soft background like pileup in the case of pp collisions or the underlying event in the case of heavy-ion collisions.

637. Joint HET/RIKEN Theory Seminar

"Maximal Flavor Violation"

Presented by Shaouly Bar-Shalom, Technion & UCI

Wednesday, August 13, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Amarjit Soni

638. Nuclear Physics & RIKEN Theory Seminar

"Is energy-momentum conservation masquerading as more interesting physics? How different are p+p and Au+Au collisions, really?"

Presented by Michael Lisa, Ohio State University

Friday, August 8, 2008, 2 pm
Small Seminar Room, Bldg. 510

Hosted by: Harmen Warringa

Transverse momentum distributions and femtoscopic measurements in ultra-relativstic heavy ion collisions carry considerable information about the dynamics of the hot system produced. Direct comparison with the same spectra from p+p collisions has proven invaluable to identify novel features associated with the larger system, in particular, the `jet quenching'' at high momentum and apparently much stronger collective flow dominating the spectral shape at low momentum. I will discuss possible hazards of ignoring conservation laws in the comparison of high- and low-multiplicity final states. I will argue that the effects of energy and momentum conservation actually dominate many of the observed systematics,