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DEC
8
Tuesday
Nuclear Physics Seminar
"Jets and Heavy Flavor at the Electron-Ion Collider"
Presented by Dr. Hai Tao Li, Argonne National Laboratory and Northwestern University
11 am, Videoconference / Virtual Event
Tuesday, December 8, 2020, 11:00 am
Hosted by: Yong Zhao
Abstract: Theoretical investigations for observables are crucial to answer fundamental questions at the future electron-Ion Collider. In this talk, I will discuss our recent theoretical works in calculating cross-sections and substructure for jets and open heavy flavor in electron-nucleus collisions. For jet production, we demonstrate theoretically how to disentangle the effects from nuclear parton distribution functions and the ones that arise from strong final-state interactions between the jet and the nuclear medium. For open-heavy flavor hadron production, we show how to identify the optimal observables, center-of-mass energies, and kinematic regions most sensitive to the physics of energy loss and hadronization at the EIC.
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Nuclear Physics Seminar
"Soft dielectron production in pp collisions at sqrt(s)=13 TeV with ALICE"
Presented by Dr. Jerome Jung, Frankfurt University
Tuesday, November 24, 2020, 11 am
Videoconference / Virtual EventHosted by: Takao Sakaguchi
Abstract: The production of soft photons in small systems was extensively studied in fixed-target experiments at beam momenta ranging from 10.5 to 450 GeV/c. Most experiments reported an excess of soft photons compared with the expectation from hadron decays that could not be explained by initial- and final-state bremsstrahlung. The emergence of a photon excess in a transverse momentum (pT) range far below 0.2 GeV/c was dubbed the soft-photon puzzle. At the Intersecting Storage Rings (ISR) at CERN, also an excess of dielectrons had been measured at low invariant mass and small pair pT_ee in pp collisions at sqrt(s) = 63 GeV. In ALICE the reconstruction efficiency of low-pT electrons can be increased by reducing the magnetic field of the central barrel solenoid. This allows a better electron background rejection and simultaneously enables the investigation of a kinematic domain at low dielectron invariant mass m_ee and pair transverse momentum pT_ee similar to that of the ISR experiment, which was previously inaccessible at the LHC. In this talk, a measurement of dielectron production in proton-proton (pp) collisions at sqrt(s) = 13 TeV, recorded with the ALICE detector at the CERN LHC, will be presented. The data set was taken with a reduced magnetic solenoid field of 0.2 T. The cross section for dielectron production is studied as a function of mee, pT_ee, and event multiplicity dNch/deta. Comparison of the measured dielectron yield to the hadronic decay cocktail at 0.15
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Center for Functional Nanomaterials Seminar
"Correlation of Optical and Structural Properties of Van der Waals Heterostructures and Interfaces"
Presented by HaeYeon Lee, Massachusetts Institute of Technology
Friday, November 20, 2020, 2 pm
ZoomGovHosted by: Mircea Cotlet
Van der Waals (vdW) layered materials open up new opportunities in modern electronics as they can be readily isolated into atomically thin monolayers, resulting in two-dimensional (2D) confinement of carriers. vdW heterostructures formed by stacking these 2D materials as building blocks have a wide range of optoelectronic properties and unprecedent physical phenomena. By using cathodoluminescence in electron microscope, I will show here how the structural properties of interfaces of vdW heterostructures play roles in the optical emission and charge carrier transport. In particular, I will discuss the effect of (1) twisted interface, (2) heterointerface, and (3) deformed (curved) interface on the luminescence. I demonstrate (1) tunable optical emission controlled by twist angle, (2) nanoscale optical/structure characterization of a monolayer transition metal dichalcogenides, and (3) enhanced luminescence by optical cavity effect of vdW heterostructures.
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Nuclear Physics & RIKEN Theory Seminar
"Surprises in large Nc Thermodynamics"
Presented by Thomas Cohen, Maryland U.
Friday, November 20, 2020, 9 am
Videoconference / Virtual EventHosted by: Yoshitaka Hatta
Abstract: This talk discusses some recent results in the thermodynamics of QCD in the limit where the number of colors,Nc, is large. It has long been known that there are very strong reasons to believe that large Nc QCD, unlike QCD with Nc=3, has a first order phase transition at zero chemical potential. This implies the existence of metastable superheated and supercooled regimes. Recently some remarkable properties of these phases have been elucidated, most dramatically the fact that the metastable supercoloed plasma phase at large Nc will have negative absolute pressure—a pressure below that of the vacuum.
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Particle Physics Seminar
"The XENON1T Low-Energy Excess and Other Exciting Results"
Presented by Dr Erwann Masson, IJCLab/CNRS - Université Paris-Saclay
Thursday, November 19, 2020, 3 pm
WebcastHosted by: Hanyu Wei
Abstract: For more than a decade, the XENON Collaboration has been designing and operating a family of liquid xenon-filled detectors with the aim of catching dark matter Weakly Interacting Massive Particles (WIMPs). Although the road to discovery did not come to an end yet, the successive XENON detectors always placed the most stringent limits to the WIMP mass and interaction cross section with ordinary matter, in particular thanks to their highly controlled radioactive environment. Taking advantage of years of thorough R&D in the subject, the latest of our running experiments, XENON1T, proved to be the most sensitive detector for WIMP direct search to date. Despite being first optimised for the observation of WIMP-induced xenon nuclear recoils, the unprecedented low electronic background of 76 events per (tonne × year × keV) in the 1–30 keV range achieved by the XENON1T experiment made it sensitive to phenomena manifested by low-energy electron recoils. Recently, the XENON Collaboration reported an excess of such events which has been interpreted as a possible evidence of new physics (solar axions, a neutrino magnetic moment or bosonic dark matter) or by the presence of unexplored background sources so far (tritium and argon). After an introduction to dark matter direct detection with XENON1T and a review of its main contributions to the field, this result will be discussed in detail, from the analysis to interpretations of the observed excess.
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RIKEN Seminar
"Correlated Dirac eigenvalues and axial anomaly in chiral symmetric QCD"
Presented by Heng-Tong DING, Central China Normal University
Thursday, November 19, 2020, 9 am
Videoconference / Virtual EventHosted by: Akio Tomiya
Abstract: How axial anomaly manifests itself in the two-point correlation functions of iso-triplet scalar and pseudo-scalar mesons affects the nature of chiral phase transition. In this talk we first review current status on the fate of UA(1) anomaly in the finite temperature lattice QCD, and then present a first continuum and chiral extrapolation of two UA(1) measures in (2+1)-flavor lattice QCD at 1.6Tc. After continuum and chiral extrapolations we find that axial anomaly remains manifested in the 2-point correlation functions of scalar and pseudo-scalar mesons in the chiral limit. To study the origin of the axial anomaly we propose novel relations between the quark mass derivatives of Dirac eigenvalue spectrum ρ and correlation functions among eigenvalues. We find that the peak structure developed in ρ in the infrared region with its height proportional to quark mass squared is responsible for the manifestation of axial anomaly. These findings suggest that the axial anomaly is driven by the weakly interacting (quasi-)instanton gas motived ρ at T>1.6Tc and the chiral phase transition belongs to 3-d O(4) universality class. The talk is based on https://arxiv.org/abs/2010.14836.
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HET Seminar
"Sommerfeld effect at the next-to-leading order for Wino dark matter"
Presented by Robert Szafron, CERN
Wednesday, November 18, 2020, 2:30 pm
Videoconference / Virtual EventHosted by: Peter Denton
Abstract: I will discuss the computation of the Sommerfeld enhancement factor for the wino dark matter at the next-to-leading order. First, I will introduce the effective field theory framework, and I will show how to calculate the correction to the Yukawa potential generated by the exchange of gauge bosons in the Standard Model. This effect leads to a sizeable modification of the annihilation cross-section, particularly near the resonance region, where it shifts the resonance position. Finally, I will discuss how these corrections influence relic abundance.
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Nuclear Physics & RIKEN Theory Seminar
"Heavy quark diffusion constant from the lattice"
Presented by Viljami Leino, Munich Tech. U.
Friday, November 13, 2020, 9 am
Videoconference / Virtual EventHosted by: Yoshitaka Hatta
In this talk I will report our recent results on the computation of the heavy quark momentum diffusion coefficient from the correlator of two chromoelectric fields attached to a Polyakov loop in pure SU(3) gauge theory on lattice. We measured the diffusion coefficient on very wide range of temparatures from 1.1Tc to 10^4Tc. We see an agreement to perturbation theory at very high temperatures and can for the first time fit a temperature dependence of this quantity.
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Particle Physics Seminar
"Hunting for new physics using long-lived particles"
Presented by Kate Pachal, Duke University
Thursday, November 12, 2020, 3 pm
WebcastHosted by: Elizabeth Brost
In the last few years, interest in long-lived particle signatures at colliders has been growing, but the field itself is still under-explored. This seminar will discuss the motivation for long-lived particle searches, particularly as they relate to Dark Matter models, give an overview of the methods and challenges involved, and talk about some specific examples from the ATLAS collaboration. Between the opportunities for technical improvements and the unusually strong dependence of analysis sensitivity on luminosity, these signatures are among the most exciting targets for the LHC Run 3. There is a lot of interesting work still to be done before the full potential of these searches will be reached!
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CFNS seminar
"Studies on exotic hadrons at LHCb"
Presented by Dr. Liupan An, Sezione, INFN di Firenze
Thursday, November 12, 2020, 10 am
Videoconference / Virtual EventHosted by: Yong Zhao
Abstract: Exotic hadrons, which are composed of more than three valence quarks, can provide new insights into the internal structure and dynamics of hadrons, thus improving our knowledge of the non-perturbative regime of QCD. Since 2003, various candidates for exotic states have been observed, to which the LHCb experiment has made major contributions. This seminar discusses the studies on exotic hadrons at LHCb. The most recent observation of structure in the $J/\psi$-pair invariant mass spectrum and study of resonant structure in $B^+ \to D^+ D^- K^+$ decays are presented.
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Nuclear Physics Seminar
"Nucleon clustering at freezeout, far from and close to the QCD critical point"
Presented by Edward Shuryak
Tuesday, November 10, 2020, 11 am
Videoconference / Virtual EventHosted by: Jiangyong Jia
Clustering of nucleons at freezeout has been studied by a number of theoretical tools, including semiclassical (fluctons), hyperharmonics and, lately, direct Path Intergal Monte Carlo. It was found to be effective starting from four nucleons, with ``preclusters" feeding into multiple bound states decaying into channels with light nuclei d,t,He3 and affecting proton distribution (kurtosis). It was further found that even a minor increase of the range of nuclear forces increases clustering dramatically. Furthermore, if there exists the QCD critical point (CP) with large correlation length ξ, attraction due to binary forces becomes unrealistically large. The resolution of this paradox was found to be due to repulsive many-body forces near CP, overcoming the binary attraction and effectively suppressing clustering. We briefly discuss current experimental data and point out locations hinting at certain drop in clustering.
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Nuclear Physics & RIKEN Theory Seminar
"Deterministic Fluctuating Hydrodynamics and Relativistic Heavy-Ion Collisions"
Presented by Dr Xin An, North Carolina State University
Friday, November 6, 2020, 9 am
https://bluejeans.com/229416130Hosted by: Yoshitaka Hatta
Abstract:Fluctuations are important measures in relativistic heavy-ion collisions, in particular near the QCD critical point. In this talk, I will discuss the state-of-the-art formalism for the deterministic fluctuating hydrodynamics, and connect it to the ongoing Beam Energy Scan Program at RHIC. I will also address recent progress in the dynamics of non-Gaussian fluctuations.
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Particle Physics Seminar
"Preparing CMS for the HL-LHC and the future of computing"
Presented by Allison Hall, Fermilab
Thursday, November 5, 2020, 3 pm
WebcastHosted by: Elizabeth Brost
Abstract: The High Energy Physics (HEP) community is approaching the High-Luminosity LHC (HL-LHC) upgrade, where the instantaneous luminosity will increase by a factor of 10 relative to the LHC design. This will provide exciting physics opportunities but also unprecedented computing challenges for the CMS and ATLAS experiments. In this talk, I will cover two innovative R&D efforts designed to help reduce the computing requirements and maximize the discovery potential of the HL-LHC. The first initiative is the Compact Framework for Effective Analysis (Coffea), the first fully functioning HEP analysis framework based on the usage of Big Data technologies. The second project is the mkFit algorithm, a highly parallelized version of the traditional Kalman filter algorithm for charged particle tracking. Through the efficient use of modern CPU architectures, mkFit has achieved a factor of 6 speedup with respect to the nominal CMS algorithm, with comparable physics performance. Lessons learned and future opportunities and plans will be discussed.
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RIKEN Seminar
"Matter and radiation in the fragmentation region of heavy-ion collisions"
Presented by Dr Isobel Kolbe, University of Washington
Thursday, November 5, 2020, 11 am
https://bluejeans.com/572844260Hosted by: Akio Tomiya
Abstract: We study the fragmentation (far forward/backward) region of heavy-ion collisions by considering an at-rest nucleus which is struck by a relativistic sheet of colored glass. By means of a simple classical model, we calculate the subsequent evolution of baryons and the associated radiation. We confirm that the struck nucleus undergoes compression and that the dynamics of the early times of the collision are best described by two separate fluids as the produced radiation's velocity distribution is very different to the velocity distribution of the matter in the struck nucleus. (Based on https://arxiv.org/abs/2009.05680)
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Condensed-Matter Physics & Materials Science Seminar
"Spin Orbital Dimer Singlets and Vibronic Fluctuations in a Cluster Mott Insulator"
Presented by Kemp Plumb, Brown University
Thursday, November 5, 2020, 11 am
Virtual SeminarHosted by: Mark Dean
The spatially anisotropic character of d-orbitals in transition metal compounds can lead to many and diverse 'quantum' phases of matter when spin orbit coupling is on equal footing with with electronic correlations. These phases include multi-polar orders, spin liquids, and/or spin orbitals liquids. The most celebrated example is the Kitaev model for j=1/2 Kramers doublets on the honeycomb lattice. When orbital degeneracy is introduced, the resulting orbital fluctuations open up many unexplored possibilities. In this seminar, I will introduce the cluster Mott insulating lacunar spinels as class of model materials where correlations, spin orbit coupling, and orbital degeneracy act in concert to produce several interesting magnetic phases. Following this, I will present a set of neutron scattering results on one member of this family: GaTa4Se8, a material that realizes j=3/2 model on the FCC lattice. We observe that the ground state of GaTa4Se8 is a spin-orbital dimer singlet phase and capture the collective magnetic excitations from that state. Intriguingly, the dimerization transition is preceded by a regime of dynamic vibronic fluctuations extending to temperatures four times higher than the global symmetry breaking transition. I will discuss these results in relation to the quadrupolar ordering transition recently proposed for the sister compound GaNb4Se8. Zoom Meeting https://bnl.zoomgov.com/j/1608389385?pwd=QWNXbnFTOXVyQkFBU2o3ZGFjZ2pIdz09&from=msft
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HET Seminar
"A new paradigm for particle cosmology"
Presented by Azadeh Maleknejad, CERN
Wednesday, November 4, 2020, 2:30 pm
https://bluejeans.com/767813754Hosted by: Julia Gehrlein
Abstract: Modern cosmology has been remarkably successful in describing the Universe from a second after the Big Bang until today. However, its physics before that time is still much less certain. It profoundly involves particle theory beyond the Standard Model to explain long-standing puzzles: the origin of the observed matter asymmetry, nature of dark matter, and cosmic inflation. In this talk, I will explain that fractions of a second after the Big Bang, relic axion-gauge fields can possibly relate and explain these seemingly unrelated phenomena in early and late cosmology. Moreover, these relics would provide a new window into the early Universe in the form of primordial chiral gravitational waves. This mechanism can possibly lead to a new paradigm for particle cosmology, and its smoking gun signature is testable by future CMB missions.
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HET Lunch Seminar
"CP Violation at Long-Baseline Neutrino Experiments"
Presented by Peter Denton, BNL
Friday, October 30, 2020, 12:15 pm
https://bluejeans.com/972135006Abstract: The nature of CP violation in the lepton sector is one of the biggest open questions in particle physics. Long-baseline accelerator experiments have the opportunity to determine if CP is violated in the mass matrix. I will discuss some theoretical issues about how CP is parameterized and, in particular, that using δ is misleading. Then I will look at the most recent NOvA and T2K data which show a slight and very interesting tension. While this tension possibly indicates a flipping in the mass ordering, it is better fit by new physics such as NSI with an additional source of CP violation. The strength of this NSI can be easily estimated analytically and I will present a numerical analysis of the preferred regions which are generally consistent with other constraints.
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Particle Physics Seminar
"Evidence for Higgs boson decay to a pair of muons from the CMS experiment"
Presented by Nan Lu, California Institute of Technology
Thursday, October 29, 2020, 3 pm
WebcastHosted by: Elizabeth Brost
Abstract: This seminar presents the search for the rare Higgs boson decay to a pair of muons performed by the CMS experiment at the LHC, based on the full Run 2 dataset. Events are categorized based on the characteristics of major Higgs boson production mechanisms and are analyzed using machine learning techniques, which significantly boosts the sensitivity of the search. A 3.0σ excess is observed in data, constituting the first evidence for the Higgs boson coupling to muons.
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HET Seminar
"Cosmological phase transition of composite Higgs confinement and the fifth dimension"
Presented by Majid Ekhterachian, University of Maryland
Wednesday, October 28, 2020, 2:30 pm
https://bluejeans.com/767813754Hosted by: Julia Gehrlein
Abstract: I will discuss the cosmological (de)confinement phase transition (PT) of nearly conformal, strongly coupled large N field theories, applicable to composite Higgs models, using their holographic dual 5D formulation. In this description, the PT is from the high temperature phase in which the IR of the warped extra dimension is covered by a black-brane horizon to the low temperature Randall-Sundrum-1 phase. The PT proceeds by percolation of IR-brane bubbles nucleating from the horizon, and the bubble dynamics during the PT sources a stochastic gravitational wave background that can be detected by future experiments. I will show how to construct a smooth "bounce" configuration that interpolates between the two phases, allowing for a controlled description of bubble nucleation within 5D EFT. We will see that the cosmological PT in the minimal models can complete only after a large period of supercooling, potentially resulting in excessive dilution of primordial matter abundances. I will then show how generic modifications of the minimal models can result in a much faster completion of the PT. Finally, I will discuss the gravitational wave signal produced by the PT and the implications of the PT for baryogenesis.
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NT/RIKEN seminar
"Correlations, fluctuations and the QCD phase diagram"
Presented by Volker Koch, LBNL
Friday, October 23, 2020, 3:30 pm
https://bluejeans.com/572303901Hosted by: Yoshitaka Hatta
Abstract: I will discuss what we have so far learned about the QCD phase diagram by studying correlations and fluctuations. I will also address recent progress in relating lattice QCD results to actual measurements.
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Leona Woods Awardee Seminar
"Many (Weakly Coupled) Hadrons in a Box"
Presented by Dorota Grabowska, CERN
Wednesday, October 21, 2020, 2:30 pm
https://bluejeans.com/767813754Hosted by: Sally Dawson
Abstract:Lattice methods provide the only known tool to calculate, from first principles and with quantifiable errors, properties of nuclear systems. In particular, the Luscher quantisation condition, as well as its generalisations, allow for the extraction of infinite volume scattering information from finite volume energy shifts. Unfortunately, while the quantisation condition itself can be written in a fairly compact way, applying it to real-world simulations is a different matter. In this talk, I will present new tools and methods which aim to maximise the amount of information that can be gleaned from the simulations of weakly interacting few body systems.
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Leona Woods Awardee Colloquium
"The Curious Case of Life on the Lattice"
Presented by Dorota Grabowska, CERN
Tuesday, October 20, 2020, 3:30 pm
https://bluejeans.com/308299597Hosted by: Peter Steinberg
Abstract: After decades of both theoretical and experimental efforts, the Standard Model of Particle Physics is complete. While this represents an incredible achievement, we also know this is not the full story. The gaps in our understanding include the nature of dark matter and neutrino masses, as well as potential flavour anomalies and the lack of constraints for non-perturbative observables. One of the tools that physicists use to fill in some of these gaps is Lattice Field Theory. By discretising spacetime, not only is the UV behaviour of the theory rendered finite, but it also becomes well suited to numerical methods. For example, lattice methods are what allows physicists to carry out first principle explorations of the low energy spectrum of QCD. However, working at finite lattice spacing and in finite volumes carries a cost — things that we take for granted in the continuum may no longer hold. In some cases, the result is a theoretical issue, where we are simply not sure how to write down the desired theory on a discretised spacetime. Other times, what results are numerical limitations, where finite resources require the development of clever algorithms and new methodologies. In this talk, I will focus on two questions — how to implement chiral gauge theories on the lattice and how to extract scattering information from finite volume measurements — in order to demonstrate that while life on the lattice is not always simple, the payoff is very much worth it.
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NT/RIKEN seminar
"The quest for explaining the top-row CKM unitarity deficit"
Presented by Chien Yeah Seng, Bon
Friday, October 16, 2020, 9 am
https://bluejeans.com/534115036Hosted by: Yoshitaka Hatta
Abstract: Symmetries of the weak sector of the Standard Model and its completeness find an exact mathematical realization in the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix. Of various relations among its elements, the top-row unitarity relation is by far the one known with the highest precision. The last few years have seen a rapid development in both the theory and experiments related to the extraction of the top-row CKM matrix elements and the respective unitarity relation, as quoted in the 2020 PDG: |V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=0.9985(3)_{V_{ud}}(4)_{V_{us}}. The apparent 3sigma deviation from unitarity points towards the possibility of BSM physics. Therefore, it is important to further reduce all the SM uncertainties in both V_{ud} and V_{us} in order to reach a level sufficient to claim a discovery. This involves a better understanding of various QCD matrix elements that enter the beta decays of neutron, nuclei and kaon, in particular those governing the electromagnetic radiative corrections (EMRC) in such processes. In this talk I will briefly describe the recent progress along this direction and discuss possible improvements in the future.
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CFNS seminar
"Signature of gluon saturation: from STAR to EIC"
Presented by Dr. Xiaoxuan Chu, BNL
Thursday, October 15, 2020, 4 pm
https://bluejeans.com/240467456/5520Hosted by: Jinlong Zhang
Abstract: The gluon parton distribution function (PDF) grows with lower and lower x very fast. As the total scattering cross section is bound by quantum mechanics, the raise of the gluon density has to be tamed. A definitive discovery of non-linear effects in QCD and as such the saturation regime would significantly improve our understanding of the proton structure and of nuclear interactions at high energy. Data recorded during the 2015 RHIC run with the STAR Forward Meson Spectrometer (FMS, 2.6 ≤ η ≤ 4.0), allow to measure the azimuthal correlation between two particles, which has been proposed to be one of the most direct and sensitive channels to access the underlying nonlinear gluon dynamics. In this talk, we will present new results for di-hadron correlations as a function of A and transverse momenta in p+p, p+Au and p+Al collisions at STAR. New opportunities for measurements with the STAR forward upgrade and future EIC to study non-linear effects in QCD will also be discussed.
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Particle Physics Seminar
"Resistive readout in silicon detector"
Presented by Nicolo Cartiglia, INFN
Thursday, October 15, 2020, 3 pm
WebcastHosted by: Elizabeth Brost
Abstract: In this seminar, I will present the implementation of the resistive readout principle to the silicon detector. Resistive Silicon detectors, also known as AC-LGADs, are a new kind of silicon detector that uses the combination of a continuous resistive readout electrode with AC readout to share the signal among pads. In this design, the signal is collected on a continuous resistive electrode, and it is AC-coupled to pixel electronics. This technique leads naturally to signal sharing among pads, even in very thin sensor and without an external magnetic field. Our prototypes have shown that resistive readout works remarkably well, and, using the shared signals, the position resolution is extremely good (3-5 um), even with large pads (200-300 um). These new sensors, combining internal gain and internal sharing, provide very good temporal resolution (~30-40ps), have a 100% fill factor, and are ideal for systems requiring a very low material budget.
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NT/RIKEN seminar
"Groomed and energy-energy correlation event shapes in DIS"
Presented by Yiannis Makris, INFN, Pavia
Friday, October 9, 2020, 9 am
https://bluejeans.com/927877926Hosted by: Yacine Mehtar-Tani
Abstract: With the future electron-ion collider data estimated to arrive in a decade, the need for theoretical and phenomenological tools to understand deep inelastic scattering (DIS) events has never been more urgent. In this seminar I will discuss early steps towards this direction. Specifically, I will focus on the adaptation to DIS of: i) the modified MassDrop Tagger grooming algorithm (mMDT) ii) and energy-energy correlation (EEC) event shape. Our adaptation relies on the geometrical separation of initial and final state radiation in the Breit frame, where I will establish the definitions of the proposed observables. The novel grooming procedure, although similar to mMDT, employs the Centauro measure used in the novel jet algorithm tailored to the needs of DIS. The groomed 1-jettiness will also be discussed.
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CFNS seminar
"A novel compact detector concept for the Electron-Ion Collider"
Presented by Prof. Pawel Nadel-Turonski, Stony Brook University
Thursday, October 8, 2020, 4 pm
https://bluejeans.com/240467456/5520Hosted by: Yong Zhao
Abstract: The Electron-Ion Collider (EIC) at Brookhaven National Laboratory is the next-generation US facility for "cold QCD" science, which includes understanding the spin structure of the proton and the spatial structure of the glue in nucleons and nuclei. The EIC will be the first collider capable of storing polarized electrons, protons, and light ions. It will also be able to accelerate all ions from deuterium to uranium. To support this extensive program, the collider will need one, and preferably two, general-purpose detectors. A unique challenge of the EIC detector is the inherent asymmetry between the two beam directions, both in terms of particle species and momenta, and the physics (low-x hadrons, for instance, tend go more in the electron beam direction while high-x ones go in the hadron beam direction). The resulting detector thus not only needs a fully hermetic suite of subsystems for tracking, calorimetry, and particle identification (which is of particular importance to EIC physics), but also needs to satisfy very different requirements at different angles (pseudorapidities) – and it needs to accomplish all of this within a moderate budget. This presentation will cover some of the key physics opportunities and requirements at the EIC, followed by a detailed look at an affordable compact EIC detector concept that makes it possible to reach all performance goals. As the name suggests, it does this by employing a combination of technologies that allows reducing cost by reducing subsystem size rather than compromising quality. The compact design is also beneficial for subsystem integration and integration into the interaction region of the accelerator.
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NT/RIKEN seminar
"Quark matter cores in massive neutron stars"
Presented by Aleksi Vuorinen, University of Helsinki
Friday, October 2, 2020, 9 am
https://bluejeans.com/572303901Hosted by: Semeon Valgushev
Confirming or ruling out the existence of deconfined quark matter inside neutron stars is one of the most prominent open problems in nuclear astrophysics. While the ultimate goal continues to be the observation of a smoking gun signal directly indicating the presence or creation of quark matter, a more indirect approach to the problem has lately become feasible. By combining ab-initio theoretical results for the microscopic properties of dense QCD matter with the latest astrophysical measurements of neutron star properties, it is possible to build stringent model-independent constraints for the material properties of neutron-star matter at different densities. Presenting results from a very recent analysis of this kind, we argue that matter in the cores of the heaviest stable neutron stars has characteristics considerably closer to the predicted properties of deconfined quark matter than those of nuclear matter. The implications of this finding as well as potential ways of improving its accuracy are also discussed.
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HET Seminar
"The B → D∗lν semileptonic decay at non-zero recoil from lattice QCD"
Presented by Alejandro Vaquero, University of Utah
Wednesday, September 30, 2020, 2:30 pm
https://bluejeans.com/767813754Hosted by: Julia Gehrlein
Abstract: A very rich place to look for phenomena to challenge our current understanding of physics is the flavor sector of the Standard Model (SM). In particular, the $V_{cb}$ matrix element of the CKM matrix is the subject of a long standing tension, depending on whether it is determined using inclusive or exclusive methods. On top of that, the current HFLAV average of $R(D^\ast)$ shows a 3$\sigma$ tension between experiment and the SM calculations. Theoretical support is urgently needed, and in this work I present an almost finished lattice QCD calculation of the form factors for the decay $B\rightarrow D^\ast\ell\nu$ at non-zero recoil. This analysis includes 15 MILC asqtad ensembles with $N_f=2+1$ flavors of asqtad sea quarks. The lattice spacing ranges from $a\approx 0.15$ fm down to $0.045$ fm, whereas the ratio between the light and the strange quark mass ranges from 0.05 to 0.4. The valence $b$ and $c$ quarks are treated using the Wilson-Clover action with the Fermilab interpretation, whereas the light sector employs asqtad staggered fermions. After the form factors are extrapolated to the physical point and the continuum limit in the small recoil range, these are extended to the whole kinematic range by using a model-independent parametrization. Comparison with current experimental results coming from Belle and BaBar follows, as well as a joint fit to extract the matrix element $|V_{cb}|$. The lattice prediction for the differential decay rate can be integrated to determine $R(D^\ast)$ using only lattice data.
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Nuclear Physics Seminar
"Probing QGP by semi-inclusive gamma+jet measurement at STAR"
Presented by Dr Nihar Sahoo, Texas A&M University
Tuesday, September 29, 2020, 11 am
https://bluejeans.com/165700359Hosted by: Rongrong Ma
Jet-quenching is attributed to the modification of parton shower in the Quark-Gluon Plasma (QGP). Jet recoiling from highly energetic direct photon (γ+jet) is considered as one of the valuable probes to study the inner working of the QGP at varying resolution scales. I will discuss the semi-inclusive γ+jet (and hadron +jet) measurement in central Au+Au collisions at a center of mass energy of 200 GeV in STAR. Discussions on the theory comparisons to the data and comparison of in-medium energy loss between RHIC and the LHC will be discussed. Finally, I will also shed light on the prospect of STAR jet measurements in this direction.
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NT/RIKEN seminar
"New applications of dipole Monte Carlo implementations"
Presented by Christian Bierlich, Lund University
Friday, September 25, 2020, 9 am
https://bluejeans.com/640344386Hosted by: Yoshitaka Hatta
With data for small system collectivity getting ever more precise and diverse, and new experiments such as the EIC promise data with unprecedented geometric control, Monte Carlo generators face the requirement of a space-time picture of the initial state, to complement the more traditional momentum-space one. In this seminar I will present how the Muller dipole model has been used to that effect, previously in the DIPSY event generator, and is now being used in PYTHIA as well. Since all parameters of the model can be fitted to inclusive quantities, it offers a solid starting point for such efforts. Furthermore, since the model calculates projectile and target Fock states event-by-event, color fluctuations of the nucleon-nucleon, or γ*-nucleon, cross-section comes about as a by-product. Finally, once there is an initial space-time structure, a mechanism is needed to transport initial state anisotropies to the final state. Over the past years we have developed a model based on interacting strings, with exactly this aim. I will discuss recent developments, with a focus on response to initial state geometry, and similarities to hydro.
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Particle Physics Seminar
"Recent measurements of Vector Boson Scattering at CMS"
Presented by Aram Apyan, Fermi National Accelerator Laboratory
Thursday, September 24, 2020, 3 pm
WebcastHosted by: Viviana Cavaliere
The observation of a Higgs boson at the LHC in 2012 presents a new paradigm of precision physics aiming at the investigation of the Electroweak (EW) symmetry breaking. The study of VBS processes provides key insight into the Higgs sector as well as the self-interactions of W and Z bosons through triple and quartic gauge couplings. I will show the first observation of the EW WZ production with the CMS detector along with the first detailed characterization of the same-sign EW WW production. The most stringent constraints on the structure of quartic vector boson interactions in the framework of dimension-8 effective field theory operators are reported. The scattering of longitudinally polarized W and Z bosons is a particularly interesting probe of the SM, as its tree-level amplitudes would violate unitarity at high energies without delicate cancellations from quartic gauge couplings and Higgs-boson contributions. I will show the first measurement of the scattering of polarized same-sign W boson pairs
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NT/RIKEN seminar
"Loop, String, and Hadron Dynamics in SU(2) Hamiltonian Lattice Gauge Theories"
Presented by Dr Jesse Stryker, U. Washington
Friday, September 18, 2020, 11 am
https://bluejeans.com/273012913Hosted by: Yoshitaka Hatta
We present a reformulation of an SU(2) Hamiltonian lattice gauge theory—-a loop-string-hadron (LSH) formulation—-that characterizes dynamics directly in terms of its loop, string, and hadronic degrees of freedom, while alleviating several apparent disadvantages of quantumly simulating the Kogut-Susskind formulation. This LSH formulation, derived from Schwinger bosons, extends the local loop formulation of (d+1)-dimensional lattice gauge theories by incorporating staggered quarks, furnishing the algebra of gauge-singlet operators, and succinctly encoding the dynamics among states having Gauss's law built in to them. LSH operators are factored into explicit products of "normalized'' ladder operators and diagonal matrices, priming them for applications in quantum algorithms. Self-contained translations of the Hamiltonian are given and I comment on the next steps for this framework.
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Particle Physics Seminar
"New Mission Concept: Galactic Explorer with Coded Aperture Mask Compton Telescope (GECCO)"
Presented by Alexander Moiseev, University of Maryland, CRESST/NASA Goddard Space Flight Center
Thursday, September 17, 2020, 3 pm
https://bluejeans.com/845693053Hosted by: Anze Slosar
We present a novel concept for a next-generation γ-ray telescope that will cover the hard X-ray - soft γ-ray region. Despite the progress made by the European Space Observatory INTEGRAL, this energy range is still under-explored. GECCO will conduct high-sensitivity measurements of the cosmic γ-radiation in the energy range from 100 keV to ∼10 MeV and create intensity maps with high spectral and spatial resolution, focusing on sensitive separation of diffuse and point- source components. These observations will enable the following major objectives for GECCO: a) understand the nature of the central supermassive black hole environment and sources at the Galactic Center (GC); b) resolve heavily populated sky regions, including tangential directions to the spiral arms in the Galactic plane; c) localize and discern the origin(s) of the 511 keV positron annihilation line; d) decipher the origin(s) of the Fermi Bubbles by mapping the Bubbles and especially their bases near the GC; e) resolve Galactic chemical evolution and sites of explosive element synthesis by conducting high-sensitivity measurements of nuclear lines; f) test as-yet unexplored candidates for the dark matter. The instrument is based on a novel CdZnTe Imaging calorimeter and a deployable coded aperture mask. It utilizes a heavy-scintillator shield and plastic scintillator anti-coincidence detectors. The unique feature of GECCO is that it combines the advantages of two techniques – the high-angular resolution possible with coded mask imaging, and a Compton telescope mode providing high sensitivity measurements of diffuse radiation. With this combined "Mask+Compton" operation we will separate diffuse and point-sources components in the GC radiation with high sensitivity. GECCO will be operating mainly in the pointing mode, focusing on the Galactic Center and other regions of interest. It can be quickly re-pointed to any other region, when alarmed. Expected GECCO performance is as follows: energy resolution
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NT/RIKEN Seminar
"On next to soft corrections to Inclusive cross sections at the colliders"
Presented by Vajravelu Ravindran
Friday, September 11, 2020, 9 am
https://bluejeans.com/849527782Hosted by: Yoshitaka Hatta
We present [hep-ph/2006.06726] a framework that resums threshold enhanced large logarithms to all orders in perturbation theory for inclusive processes such as the production of a pair of leptons in Drell-Yan process and of Higgs boson in gluon fusion as well as in bottom quark annihilation at the hadron colliders. In addition, we apply [hep-ph/2007.12214] this to Deep Inelastic Scattering (DIS) and hadron production in Semi-Inclusive Annihilation (SIA) of electron positron colliders. These logarithms include the distributions P(log?^i (1−z))/1−z)) resulting from soft plus virtual (SV) and the logarithms log?^i (1−z) from next to SV contributions. We use collinear factorisation and renormalisation group invariance to achieve this. We find that the resummed result is a solution to Sudakov type differential equation and hence it can predict soft plus virtual contributions as well as next to SV contributions to all orders in strong coupling constant to the partonic coefficient function in terms of infrared anomalous dimensions and process independent functions. The z space resummed result is shown to have integral representation which allows us to resum the large logarithms of the form log?i(N) retaining 1/N corrections resulting from next to SV terms. We show that in N space, tower of logarithms are summed to all orders in strong coupling constant.
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Particle Physics Seminar
"First results on ProtoDUNE single phase LArTPC performance"
Presented by Wenqiang Gu, BNL
Thursday, September 10, 2020, 3 pm
WebcastHosted by: Hanyu Wei
ProtoDUNE-SP is the single-phase prototype for the DUNE Far Detector. Consisting of an active volume of 6m high, 7m wide and 7.2m deep (along the drift direction), ProtoDUNE-SP with a total liquid argon mass of 0.77kt represents the world largest monolithic single-phase liquid argon time projection chamber (LArTPC) ever built to date. In this talk, I will give an overview of the construction and operation of the ProtoDUNE-SP with an emphasis on the first results of the detector performance and critical detector calibrations. The measured performance meet or exceed the specifications for the DUNE far detector, in several cases by large margins. ProtoDUNE-SP's successful operation starting in 2018 and its production of large samples of high-quality data demonstrate the effectiveness of the single-phase far detector design. Zoom connection https://fnal.zoom.us/j/95125205396?pwd=NU52VklIYTk4UGRNdGRDY1FIQ0lNZz09 Meeting ID: 951 2520 5396 Passcode: 920041
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Nuclear Physics Seminar
"What can stop the flow? Azimuthal anisotropies at large mass, high pT, and in extremely small systems with ATLAS"
Presented by Dennis Perepelitsa, University of Colorado Boulder
Tuesday, September 8, 2020, 11 am
https://bluejeans.com/165700359.Hosted by: Jin Huang
Experimental signatures of multi-particle collectivity persist for a broad variety of system sizes and interacting probes, such as in low-multiplicity proton-proton collisions and for charm quarks in proton-lead collisions. This behavior seems to be so ubiquitous, that it is almost as interesting to observe when a probe does not participate in the collective motion in a given system, as when it does. In this seminar, I will highlight some of our work in trying to delineate the boundaries of where collective phenomena start and stop using the ATLAS experiment at the LHC. Finding these boundaries can help better reveal the underlying dynamics of the many-body QCD systems produced in these collisions. I will discuss results on measurements of collectivity for charm- and bottom-separated heavy quarks in pp collisions, for very high-pT particles in p+Pb collisions, and in ultra-peripheral photo-nuclear collisions selected during Pb+Pb data-taking.
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NT/RIKEN seminar
"The Curious Story of the Photon"
Presented by Bowen Xiao, CCNU
Friday, September 4, 2020, 9 am
WebcastHosted by: Yoshitaka Hatta
In this talk, I will talk about several interesting and peculiar aspects of the photon in high energy scatterings. First, I will review the history of Weizsacker-Williams photon distribution in a relativistic moving charged particle in the so-called equivalent photon approximation (EPA), and discuss the extension of this method towards the photon Wigner distribution. These methods can be applied to the dilepton productions recently measured by STAR, ATLAS and CMS collaborations. In the end, I will also mention the rich QCD structure of the photon and its implication on the collective phenomenon at the future EIC. https://bluejeans.com/429607848
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CFN Virtual Colloquium
"Using Soft-Matter Physics for Nanopatterning and Nanofabrication"
Presented by Dr. Ricardo Ruiz, Lawrence Berkeley National Laboratory
Thursday, September 3, 2020, 4 pm
BlueJeans Event: https://primetime.bluejeans.com/Hosted by: Chang-Yong Nam
Macromolecular self-assembly has evolved to become an important and valuable tool for bottom-up patterning and fabrication at the nanometer scale. From block copolymer lithography to nanocrystal superlattices to biomolecular assemblies, bottom-up patterning is reaching an unprecedent level of control over complex patterns at the nanoscale with an increasing degree of precision. There is no question that the lithographic landscape has been transformed in the past few years with the introduction of extreme ultraviolet (EUV) lithography and the maturity of multiple patterning techniques. At dimensions below 10 nm, emphasis is shifting away from resolution to precision, highlighting the importance of the uniformity achieved by block copolymers and the exquisite precision afforded by biomolecular assemblies. Moreover, an opportunity may be opening for new, higher complexity, information-rich architectures where hybrid nanoparticle-(bio)molecule assemblies may shine. With features defined at the molecular level and the potential to modular and hierarchical structures, self-assembly offers a path to highly uniform, 2D and 3D architectures. In this talk I will review the current state of bottom-up patterning with soft matter and I will discuss research plans at The Molecular Foundry related to molecular-scale assembly hoping we can foster collaborations across the various NSRCs. Bio-sketch: Dr. Ricardo Ruiz is a Staff Scientist at Lawrence Berkeley National Laboratory where he uses Soft Matter Physics to solve nanofabrication challenges at the single-digit nm scale. From 2006 to 2019 he held various appointments at Hitachi GST/ HGST/ Western Digital where he contributed to magnetic bit patterned media and non-volatile memories, and he managed a research Group dedicated to block copolymer and nanoparticle lithography. He received his PhD in Physics from Vanderbilt University in 2003. He is a Fellow of the American Physical Society. To join, select from the following options: 1) Web Browser a) https://primetime.bluejeans.com/a2m/live-event/ygxfdcgf 2) Laptop paired with room system (Best Experience) a) Dial: bjn.vc or 199.48.152.152 in the room system. b) Go to https://primetime.bluejeans.com/a2m/live-event/ygxfdcgf/room-system/ c) Enter the pairing code displayed on your room system screen into your browser. 3) Room System a) Dial: bjn.vc or 199.48.152.152 in the room system. b) Enter Meeting ID: 149812585 and Passcode: 5815 4) Joining via a mobile device? a) Open this link : https://primetime.bluejeans.com/a2m/live-event/ygxfdcgf b) Download the app if you don't have it already. c) Enter event ID : ygxfdcgf 5) Phone Dial one of the following numbers, enter the participant PIN followed by # to confirm: +1 (415) 466-7000 (US) PIN 9862228 # +1 (760) 699-0393 (US) PIN 2298814590 # 6) Joining from outside the US? https://www.bluejeans.com/numbers/primetime-attendees/event?id=ygxfdcgf
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virtual NT/RIKEN seminar
"Does eta/s depend on EoS?"
Presented by Pasi Huovinen, Institute of Physics Belgrade
Friday, August 28, 2020, 9 am
WebcastHosted by: Nikhil Karthik
Extracting the shear viscosity of quark-gluon plasma from experimental data has been one of the major goals of heavy-ion physics, leading to very low values of eta/s = 1-2/4pi. Most of these works have been done using by now outdated EoS parametrization, and I'll discuss how and whether the use of contemporary EoS affects the extracted EoS in a full-fledged Bayesian analysis. I will also discuss whether the minimum value of eta/s depends on how the temperature dependence of eta/s is parametrised. bluejeans: https://bluejeans.com/826383959
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Particle Physics Seminar
"MeV-Scale Physics with Large Liquid Argon TPCs"
Presented by Dr William Foreman, Illinois tech
Thursday, August 27, 2020, 3 pm
WebcastHosted by: Hanyu Wei
Liquid argon time projection chambers (LArTPCs) are powerful detectors that combine millimeter-scale particle tracking with calorimetric capabilities, and their scalability makes them ideally suited for studying neutrino interactions. A LArTPC capability that has received relatively less attention is their low-energy threshold, which enables the study of phenomena down to the MeV scale. Here we will highlight the results from recent truth-level Monte Carlo simulations which demonstrate physics capabilities enabled by reconstruction of topologically compact and isolated low-energy features, or `blips,' in large liquid argon time projection chamber events. We show that consideration of reconstructed blips in LArTPCs can improve calorimetry for neutrino and new physics interactions and for final-state particles ranging in energy from the MeV to the GeV scale. Blip activity analysis is also shown to enable discrimination between interaction channels and final-state particle types.
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virtual NT/RIKEN seminar
"Strongly coupled QFT dynamics via TQFT coupling"
Presented by Mithat Unsal, NCSU
Friday, August 21, 2020, 9 am
https://bnl.bluejeans.com/726276981Hosted by: Nikhil Karthik
We consider a class of quantum field theories and quantum mechanics, which we couple to topological QFTs, in order to classify non-perturbative effects in the original theory. The TQFT structure arises naturally from turning on a classical background field for a discrete 0- or 1-form global symmetry present in the theory. By using this method, I prove that the the non-perturbative expansion parameter is exp[-S_I/N]= \exp[-{8 \pi^2}/{g^2N}], both in the semi-classical weak coupling domain and strong coupling domain, corresponding to a fractional topological charge configurations. To classify the non-perturbative effects in original SU(N) theory, we must use PSU(N) bundle and lift configurations (critical points at infinity) for which there is no obstruction back to SU(N). These provide a refinement of instanton sums: integer topological charge, but crucially fractional action configurations contribute.
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HET Seminar
"(undergraduate edition)] FeynGraphGen: a QGRAF-based Feynman diagram generator for Lattice QCD code generation"
Presented by Ryan Abbott
Wednesday, August 19, 2020, 2:30 pm
https://bluejeans.com/767813754Hosted by: Peter Denton
As the number number and complexity of Feynman diagrams used in lattice QCD calculations grow, it becomes desirable to have automated tools for generating Feynman diagrams and converting said diagrams to code. Current tools for graph generation (FeynArts, QGRAF) are insufficient for these purposes, so we have created a new C++ program FeynGraphGen which replicates the functionality of QGRAF and provides a scriptable Python interface suitable for Lattice QCD code generation. In this talk I will give an overview of how FeynGraphGen and QGRAF work, why previous approaches fail for Lattice QCD, and the path forward towards applying FeynGraphGen to future lattice calculations.
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RIKEN Seminar
"Quarkonium production and polarization in the color evaporation model"
Presented by Vincent Cheung, UC Davis
Thursday, August 13, 2020, 9 am
https://bluejeans.com/732452652Hosted by: Yuta Kikuchi
Quarkonium production and polarization in the color evaporation model Abstract: One of the best ways to understand hadronization in QCD is to study the production of quarkonium. The color evaporation model (CEM) and Nonrelativistic QCD (NRQCD) can describe production yields rather well but spin-related measurements like the polarization are stronger tests. In this talk, I will outline the quarkonium polarization puzzle and present recent attempts to use the color evaporation model to describe the polarization of quarkonium production.
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Physics Department Summer Lectures 2020
"Quantum Computation for Nuclear Physics"
Presented by Niklas Mueller, BNL
Tuesday, August 11, 2020, 12 pm
WebcastHosted by: Peter Petreczky
I will give an introduction into the exciting field of quantum computation and quantum simulation from the perspective of a nuclear theorists. My goal is to convince you that this potentially is the very beginning of a new era, where theorists may be able to compute things that had been impossible before. I will highlight the many connections between high energy and nuclear, condensed matter and atomic, molecular and optical physics that are inspired by advances in controlling matter at the single quantum level. These connections force us to think about old (and new) problems in very different and exciting ways.
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Physics Department Summer Lectures 2020
"From Raw Data to Physics Results"
Presented by Paul Laycock, BNL
Friday, August 7, 2020, 12 pm
WebcastHosted by: Wlodzimierz Guryn
Modern nuclear and particle physics experiments generate huge amounts of data that need to be calibrated, processed and analysed so that we can extract and publish physics results. In this talk I will describe the journey of data, from the bits that leave the detectors through its transformation into well-understood physics objects that are analysed by physicists all over the world. We will look in particular at how this exabyte scale problem requires computing and software solutions that operate on a global scale, and take a look at the challenges that still lie ahead of us.
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virtual NT/RIKEN seminar
"Conserved charges in general relativity and its implication on Oppenheimer-Volkoff equation"
Presented by Sinya Aoki, YITP, Kyoto
Friday, August 7, 2020, 9 am
WebcastHosted by: Nikhil Karthik
We present a precise definition of a conserved quantity from an arbitrary covariantly conserved current available in a general curved spacetime. This definition enables us to define energy and momentum for matter by the volume integral. As a result we can compute charges of well-known black holes just as an electric charge of an electron in electromagnetism by the volume integration of a delta function singularity. As a byproduct we show that the definition leads to a correction to the known mass formula of a compact star in the Oppenheimer-Volkoff equation. Bluejeans link: https://bnl.bluejeans.com/726276981
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CFNS seminar
"Era of Jet-SubStructure and its utility in high energy collisions"
Presented by Raghav Kunnawalkam Elayavalli, Wayne State University
Thursday, August 6, 2020, 4 pm
https://bluejeans.com/494177937Hosted by: Jinlong Zhang
Jets, originating from hard scatterings of quarks/gluons (partons), have been established as a very powerful tool of study in high energy colliders. Measurements utilizing jets have been performed at nearly all major collider experiments as probes of the standard model (and BSM), spin, polarization, fundamental QCD and also played an important role in studies of the Quark-Gluon Plasma (QGP) via parton energy loss or jet quenching. Since jet evolution in vacuum is intimately dependent on both the momentum and angular scales, disentangling these scales via jet substructure (JSS) tools can lead to a more differential study of the parton shower. In essence, understanding parton evolution and JSS in vacuum is a necessary prerequisite for qualitatively describing how jets are quenched in the QGP, which in turn leads to extracting the QGP microscopic properties via jet-tomography. In this talk, I will introduce JSS and present recent measurements from the STAR collaboration of JSS observables in p-p, p+Au and Au-Au collisions at $\sqrt{s_{NN}} = 200$ GeV. These results are aimed at describing the vacuum parton shower and study the impact of cold and hot nuclear matter effects differentially with jet topology. I will also discuss an important application JSS whereby we isolated a special selection of jets in heavy ion collisions who's energy loss mechanism can then be further studied in a differential fashion. I will conclude the talk by contextualizing these measurements and briefly discuss some ongoing work related to upcoming heavy ion runs at RHIC and at the recently approved EIC, where JSS can contribute towards studies of quantum entanglement and hadronization within jets in a clean environment.
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Physics Department Summer Lectures 2020
"Review of Linear Algebra Applications in Some Recent Neutrino Experiments"
Presented by Xin Qian, BNL
Friday, July 31, 2020, 12 pm
WebcastHosted by: Mary Bishai
Linear algebra has been widely used in physics analysis of experiments. In this talk, I am going to review some of its recent usage in detector signal processing, noise filtering, event reconstruction, and data unfolding. In particular, its connections to various numerical and analytical techniques including the Fast Fourier Transformation, the Compressed Sensing, and the biconjugate gradients stabilized method, will be discussed. Through many real world applications, we show the power of linear algebra in high-energy experiments.
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virtual NT/RIKEN seminar
"QCD factorization and resummation in the small-x regime"
Presented by Zhangbo Kang, UCLA
Friday, July 31, 2020, 11 am
https://bnl.bluejeans.com/726276981Hosted by: Nikhil Karthik
The physics of gluon saturation or color glass condensate (CGC) has been one of the main driving forces for the future Electron Ion Collider. Significant progress has been made in the theory and phenomenology for computing physics observables measured at RHIC and LHC in the past decades. However, the higher-order perturbative calculations in the CGC formalism still remains a bit elusive, especially in comparison with the conventional QCD collinear factorization in the dilute regime. In this talk, using single hadron production in proton-nucleus collisions as an example, I point out some of the interesting difficulties and demonstrate how this can be solved. For example, in the standard collinear factorization, the natural hard scale will automatically arise from a higher-order calculation, while choosing the natural rapidity scale for small-x remains quite tricky even with explicit higher-order calculation. I further show how to perform threshold resummation and demonstrate how this would solve the well-known negative cross section problem for this process.
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RIKEN Seminar
"Massive Thirring model in 1+1 dimensions from matrix product states"
Presented by C.-J. David Lin, National Chiao-Tung University, Taiwan
Thursday, July 30, 2020, 9 am
WebcastHosted by: Akio Tomiya
The method of matrix product states (MPS), as one of the tensor-network (TN) approaches, has been shown to be applicable to study 1+1 dimensional quantum field theories in the canonical formalism. In this talk, I present our work on the massive Thirring model using the MPS technique. Our work shows that the MPS method can be used to identify a Berezinskii-Kosterlitz-Thouless phase transition in the Thirring model. I will also discuss our exploratory results for real-time dynamics and dynamical phase transition. BJ link https://bluejeans.com/871723105
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HET Seminar
"Fast radio bursts from axion stars in a pulsar magnetosphere"
Presented by Bhupal Dev, University of Maryland, College Park
Wednesday, July 29, 2020, 2:30 pm
WebcastHosted by: Peter Denton
In this talk, we will present a new explanation of the mysterious Fast Radio Bursts (FRBs) in terms of axion star-neutron star encounters. As a dense axion star moves through the resonant conversion region of a neutron star magnetosphere, where the plasma-induced photon mass becomes equal to the axion mass, the axions can efficiently convert into photons, giving rise to an intense, transient radio signal. The energy released is determined by the axion star mass and conversion probability. The peak frequency of the emitted radio signal is fixed by the axion mass, while cosmological redshift and Doppler shift could give rise to a wide range of frequencies. In particular, we will show that a dense axion star with a mass ∼ 10−13 solar mass and composed of ∼ 10 μeV axions can account for most of the non-repeating FRBs in a wide frequency range. We will also comment on the repeating FRBs and on future tests of our hypothesis.
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Physics Department Summer Lectures 2020
"Searching for and understanding the quark-gluon plasma in heavy-ion collisions"
Presented by Rongrong Ma, BNL
Tuesday, July 28, 2020, 12 pm
WebcastHosted by: Wlodzimierz Guryn
Lattice-QCD predicts the occurrence of a phase transition above a critical temperature from ordinary nuclear matter to a new state of matter, usually referred to as the quark-gluon plasma (QGP), which is also believed to have existed momentarily after the Big Bang. One primary goal of the heavy-ion physics is to create and study the properties of the QGP. The last couple of decades have seen tremendous progresses in characterizing the QGP properties, thanks to the successful operation of dedicated experiments at the RHIC and the LHC. In this lecture, I will discuss the detectors designed for heavy-ion physics, and how an experimentalist turns electronic signal into physics results.
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Physics Department Summer Lectures 2020
"Using the Higgs boson to search for dark sector particles"
Presented by Ketevi Assamagan, BNL
Friday, July 24, 2020, 12 pm
WebcastHosted by: Mary Bishai
The discovery of the Higgs boson opens a new and rich experimental program that includes using the Higgs the boson to search for new particles. In this talk, I will discuss searches for dark sector particles in the decays of the Higgs Boson.
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virtual NT/RIKEN seminar
"Universal location of the Yang-Lee edge singularity in O(N) theories"
Presented by Gregory Johnson, NCSU
Friday, July 24, 2020, 9 am
WebcastHosted by: Nikhil Karthik
We determine a previously unknown universal quantity, the location of the Yang-Lee edge singularity for the O(N) theories in a wide range of N and various dimensions. At large N, we reproduce the N\to\infty analytical result on the location of the singularity and, additionally, we obtain the mean-field result for the location in d=4 dimensions. In order to capture the nonperturbative physics for arbitrary N, d and complex-valued external fields, we use the functional renormalization group approach. Bluejeans link: https://bnl.bluejeans.com/726276981
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Particle Physics Seminar
"First Measurement of CNO solar neutrinos with Borexino"
Presented by Dr Xuefeng Ding, Princeton University
Thursday, July 23, 2020, 3 pm
WebcastHosted by: Hanyu Wei
Borexino recently announced the first measurement of solar neutrinos from the CNO cycle process. The carbon-nitrogen-oxygen (CNO) cycle is one of two known sets of fusion reactions by which stars convert hydrogen to helium. It is thought to be more important in stars more massive than 1.3 solar mass or in late stages. Proposed as early as the 1930s by H. Bethe, it remains hypothetical until this work. Located at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, Borexino is a liquid scintillator detector that detects solar neutrinos by their elastic scattering on electrons. Most of the natural radioactive isotope backgrounds were removed during the purification campaign. Cosmogenic backgrounds, especially 11C, are low thanks also to the 3800-meter water equivalent of overburden and the three-fold coincidence analysis technique. The remaining backgrounds for measurement of CNO solar neutrinos are pep solar neutrinos and radioactive 210Bi. With two breakthroughs in the thermal stability of the detector and the analysis method, the 210Bi rate could be determined precisely and accurately for the CNO neutrino analysis. Finally, the absence of CNO solar neutrinos is disfavored at five sigma significance, and the flux of CNO solar neutrinos is determined to be 7.0+3.0-2.0 x 108 cm-2s-1.
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RIKEN Seminar
"Parton Distribution Functions inside Hardron from lattice QCD"
Presented by Xiang Gao, BNL
Thursday, July 23, 2020, 9 am
WebcastHosted by: Yuta Kikuchi
Due to the light-cone separation, straightforward calculation of Patron Distribution Function (PDF) is not possible using lattice QCD. The Large Momentum Effective Theory (LaMET) provides a systematic way to relate the quasi-PDF, defined by equal-time correlators at large hadron momentum state, to the PDF order by order in perturbation theory. Within the framework of LaMET, we study the pion valence PDF and the nucleon iso-vector PDFs. Our analysis use both RI-MOM and ratio-based schemes to renormalize the quasi-PDF matrix elements. We reconstruct the x-dependent, as well as infer the first few moments of the pion valence PDF. We compare nucleon iso-vector quasi-PDF matrix elements with the corresponding results of the global fits in coordinate space.
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Physics Department Summer Lectures 2020
"Astronomical CCDs"
Presented by Andrei Nomerotski, BNL
Tuesday, July 21, 2020, 12 pm
WebcastHosted by: Milind Diwan
I will review how the state-of-the-art sensors developed for astronomical applications can precisely measure the positions and shapes of billions of galaxies. The talk will also provide more detail on the camera and sensors for the Vera Rubin's Observatory Legacy Survey of Space and Time (LSST) and will discuss limitations on the achievable precision coming from the instrumentation.
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Physics Department Summer Lectures 2020
"Silicon Detectors"
Presented by Gabriele Giacomini, BNL
Friday, July 17, 2020, 12 pm
WebcastHosted by: Milind Diwan
Silicon technology is approximately 70 years old, but thousands of years have been dedicated to R&D by a multitude of researchers; the well-established microelectronic industry is based on it. Being that the silicon is sensitive to photons (from infrared to X-rays, passing through visible light and ultraviolet) and to charged particles, we can leverage the microelectronic technology to make sensors out of silicon. Silicon sensors are used in a variety of applications including scientific experiments (High Energy Physics, Astrophysics, Photon Science, etc) as well as industrial and commercial use (cameras, etc). The basic structure is the p-n junction across which a voltage is applied. When an ionizing event occurs (a photon or a charged-particle interacting with silicon), a short current pulse (~ few ns) is generated and detected by the read-out electronics. There are many kinds of silicon sensors and each one must be tailored according to the specific application. We'll give an overview of the state of the silicon technology and its different applications.
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Physics Department Summer Lectures 2020
"How to analyze charge spectra from photo-sensors"
Presented by Milind Diwan, BNL
Tuesday, July 14, 2020, 12 pm
WebcastHosted by: Mary Bishai
In this lecture, we will take a detailed look at the functioning and analysis of a common detector used in particle and nuclear physics. We will go through a detailed calculation of what we expect from a sensitive photo-multiplier tube used to detect photons. Through this calculation, you will learn the use of many tools that you already know from courses in calculus, probability and statistics, Fourier analysis, etc. In the end we will compare our results to actual measurements and discuss what we have learned and how to apply it in your laboratories.
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Nuclear Physics Seminar
"The cos 2φ azimuthal asymmetry in ρ^0 meson production in ultraperipheral heavy ion collisions."
Presented by Jian Zhou, Shandong University
Tuesday, July 14, 2020, 11 am
WebcastHosted by: Rongrong Ma
We present a detailed study of vector meson photoproduction in ultraperipheral heavy ion collisions (UPCs). Using the dipole model, we develop a framework for the joint impact parameter and transverse momentum dependent cross sections. We compute the unpolarized cross section and cos 2φ azimuthal angular correlation for ρ^0 photoproduction with φ defined as the angle between the ρ^0 's transverse spin vector and its transverse momentum. Our result on unpolarized coherent differential cross section gives excellent description to the STAR experimental data. A first comparison between theoretical calculation and experimental measurement on the cos 2φ azimuthal asymmetry, which results from the linearly polarized photons, is performed and reasonable agreement is reached. We find out the characteristic diffractive patterns at both RHIC and LHC energies and predict the impact parameter dependent cos 2φ azimuthal asymmetries for ρ^0 photoproduction by considering UPCs and peripheral collisions.
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Physics Department Summer Lectures 2020
"The Really Big Picture: Cosmology in the 21st Century"
Presented by Paul Stankus, BNL
Friday, July 10, 2020, 12 pm
WebcastHosted by: Wlodzimierz Guryn
Starting from a very basic level we review how to describe the standard Big Bang model of an expanding universe. We discuss the connection between expansion dynamics and different types of matter and energy densities, and focus on the evidence for the accelerated expansion of our Universe driven by dark energy. Different schools of observation and measurement will be mentioned and we conclude with possible projections for our (very) long-term future.
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virtual NT/RIKEN seminar
"Transverse momentum broadening in the Glasma"
Presented by Andreas Ipp, TU Wien
Friday, July 10, 2020, 9 am
WebcastHosted by: Nikhil Karthik
Jets are hard probes that originate from initial hard scatterings of the nuclei in heavy ion collisions. They acquire transverse momentum broadening through interaction with the evolving quark-gluon plasma. However, already the pre-equilibrium Glasma stage can contribute to transverse momentum broadening. In this talk, I present our recent work [1] where we calculate the contribution to transverse momentum broadening from the Glasma phase. We base our calculation on the boost-invariant 2+1D Glasma description which builds upon the Color Glass Condensate framework. Interestingly, we find strong time-dependence and anisotropic results with larger momentum broadening in the direction along the beam axis. [1] https://arxiv.org/abs/2001.10001 Bluejeans link: https://bnl.bluejeans.com/726276981
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Particle Physics Seminar
"A Bayesian Analysis of T2K's Data for the Measurement of Neutrino Oscillation Parameters"
Presented by Kevin Wood, Stony Brook University
Thursday, July 9, 2020, 3 pm
WebcastHosted by: Hanyu Wei
T2K has been accumulating data corresponding to 3.6 × 10e21 POT over the past 10 years. It has been studying neutrino oscillations by observing a disappearance of muon flavored (anti)neutrinos and the appearance of electron flavored (anti)neutrinos. In particular, the collaboration has recently published the first substantial 3-sigma constraints on the CP-violating phase, δCP, in a Nature article. The results from this analysis have since been updated to include 33% more neutrino mode data and significant improvements to the neutrino interaction and flux models. This talk will present these new results and discuss some details of the Markov Chain Monte Carlo Bayesian analysis employed in order to extract measurements of the neutrino oscillation parameters from T2K's data.
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Physics Department Summer Lectures 2020
"The electron-ion collider: A collider to unravel the mysteries of visible matter"
Presented by Elke Aschenauer, BNL
Thursday, July 9, 2020, 12 pm
https://bluejeans.com/832459133Hosted by: Wlodzimierz Guryn
Understanding the properties of nuclear matter and its emergence through the underlying partonic structure and dynamics of quarks and gluons requires a new experimental facility in hadronic physics known as the Electron-Ion Collider (EIC). The EIC will address some of the most profound questions concerning the emergence of nuclear properties by precisely imaging gluons and quarks inside protons and nuclei such as the distribution of gluons and quarks in space and momentum, their role in building the nucleon spin and the properties of gluons in nuclei at high energies. In January 2020 EIC received CD-0 and Brookhaven National Laboratory was chosen as site. This presentation will highlight the capabilities of an EIC and discuss its status, accelerator design and the concepts for the experimental equipment.
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OECD/Nuclear Energy Agency Webinar
"The Generalised Nuclear Database Structure: Establishing an International Nuclear Data Standard"
Presented by William D. Magwood, IV and David Brown
Wednesday, July 8, 2020, 7:30 am
bit.ly/3eNPsiPThursday, 8 July 2020 at 13:30-14:30 Paris time OECD/Nuclear Energy Agency HQ (Paris, France) bit.ly/3eNPsiP Nuclear data are produced by dozens of organisations around the world and shared internationally for the safe operation of nuclear power reactors, waste and reprocessing facilities, and nuclear medicine applications. The most common nuclear data format is the Evaluated Nuclear Data File 6 (ENDF-6) format. Originally designed for 1960s era punch-card readers, this format poses artificial limitations, requires legacy programming techniques, and obliges new scientists and engineers to learn outdated techniques. Recognising the need for a new format that embraces modern computer programming paradigms and can address more sophisticated user requirements, the NEA launched a project in 2013 to review the requirements for an international replacement for the ENDF-6 format. The project convened experts from major nuclear data evaluation projects worldwide and culminated in a new format specification for a Generalised Nuclear Data Structure (GNDS). Following rigorous international review, the new international standard GNDS 1.9 was published in May 2020. The NEA is hosting an expert roundtable discussion on the GNDS 1.9, its use, specifications, and the strategic vision of the project moving forward. The discussion will be moderated by William D. Magwood, IV, NEA Director-General and Dr David Brown, Deputy Head of the United States National Nuclear Data Center (NNDC), Manager of the ENDF Library Project, and Chair of the NEA Expert Group on the Recommended Definition of a General Nuclear Database Structure (GNDS). Discussants * Dr Osamu Iwamoto, Head, Japan Atomic Energy Agency (JAEA) Nuclear Data Center * Dr Jean-Christophe Sublet, Head, International Atomic Energy Agency (IAEA) Nuclear Data Services Unit * Dr Dorothea Wiarda, Research and development, Oak Ridge National Laboratory (ORNL) * Dr Caleb Mattoon, Scientist, Lawrence Livermore National Laboratory (LLNL) * Dr Fausto Malvagi, Senior Expert, French Alternative Energies and Atomic Energy Commission (CEA) The event is free and open to the public, and will feature a Q&A session afterwards. Please note that the number of participants is limited and registrations are on a first-come, first-served basis.
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Physics Department Summer Lectures 2020
"Introduction to high energy spin physics"
Presented by Yoshitaka Hatta, BNL
Tuesday, July 7, 2020, 12 pm
https://bluejeans.com/832459133Hosted by: Peter Petreczky
In the first part, I give an elementary introduction to hadron physics and QCD (Quantum Chromodynamics), and explain how scattering experiments allow us to probe the internal structure of the proton. In the second part, I focus on spin physics. I introduce the notion of spin in particle physics and then point out that understanding the spin of a composite particle (in particular the proton) is an fascinating subfield of QCD. I give an overview of the basic problems and the current experimental/theoretical status, as well as an outlook for the future.
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Physics Department Summer Lectures 2020
"A Golden Age in Physics: nuclear collisions at ultra-relativistic energies"
Presented by Rob Pisarski, BNL
Wednesday, July 1, 2020, 12 pm
https://bluejeans.com/832459133Hosted by: Peter Petreczky
I give a pedagogical introduction to gauge theories, and how they appear in the theory of strong interactions, where quarks and gluons form neutrons, protons, and other particles. I make several historical detours, to emphasize how the lore of "As everyone who is anyone knows..." has failed in physics. A brief overview of results from the Relativistic Heavy Ion Collider will be outlined, but the emphasis is on why a Quark-Gluon Plasma, created at about a trillion degrees, is a subject of fundamental interest.
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Physics Department Summer Lectures 2020
"The Hunt for the Little Neutral One"
Presented by Mary Bishai, BNL
Tuesday, June 30, 2020, 12 pm
https://bluejeans.com/832459133Hosted by: Wlodzimierz Guryn
The neutrino - the "Little Neutral One" in Italian - is one of the most mysterious of the elementary particles of physics. In this lecture we will examine the fascinating history of the neutrino and its strange properties that lead to 4 Nobel prizes and multi-billion dollar experiments.
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Nuclear Physics Seminar
"Recent STAR spin Results II"
Presented by Ting Lin and Huanzhao Liu
Tuesday, June 30, 2020, 11 am
WebcastHosted by: Salvatore Fazio
This will consist of two talks. First talk by: Ting Lin, Cyclotron Institute, Texas A&M University Title: "Azimuthal Transverse Single-Spin Asymmetries of Charged Pions Within Jets from Polarized pp Collisions at sqrt(s) = 200 GeV" Abstract: Collins effect involves convolution of the quark transversity in the proton with the spin-dependent Collins fragmentation function, leading to azimuthal modulations of identified charged hadron yields about the jet axis. We report new preliminary results for the Collins asymmetry from 2015 proton+proton collisions at sqrt(s) = 200 GeV, which probe higher momentum scales (Q2 ~ 170 GeV2) than the measurements from semi-inclusive deep inelastic scattering (Q2 < 20 GeV2) and enable the test of the evolution, universality and factorization breaking in the transverse momentum dependent (TMD) formalisms. Second talk by: Huanzhao Liu, Indiana University, Center for Exploration of Energy and Matter Title: "Measurement of transverse single-spin asymmetries for di-jet production in polarized p+p collisions at sqrt(s) = 200 GeV at STAR" Abstract: We report a new measurement of the transverse single-spin asymmetries for pair-production of jets in collisions of transversely polarized protons at sqrt(s) = 200 GeV at STAR, with data taken in 2012 and 2015. The correlation between the transverse momentum of a parton (k_T) and the transverse spin (S) of its proton, moving in the longitudinal (p) direction, is probed in the measurement, together with an estimate of the corresponding Sivers calculated based on a simple kinematic model. By employing flavor-tagging to separate u- and d-quarks, we see non-zero Sivers effects for the first time in di-jet production in transversely polarized proton collisions.
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Physics Department Summer Lectures 2020
"The Anomalous Magnetic Moment of the Muon"
Presented by Bill Morse, BNL
Friday, June 26, 2020, 12 pm
WebcastHosted by: Mary Bishai
What is a muon? Who ordered that? What is a magnetic moment? What is anomalous about the magnetic moment of the muon? Most of the time, a muon is simply a muon, but very briefly, some of the time, by Quantum Mechanics, the muon is a muon, plus an electron, plus an anti-electron, for example. How can the vacuum know about all of the standard model, and all of the new physics beyond the standard model? You will know the answer to all these interesting questions after just one hour!
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virtual NT/RIKEN seminar
"Postmerger gravitational-wave signatures of phase transitions in binary mergers"
Presented by Lukas Weih, ITP Frankurt
Friday, June 26, 2020, 9 am
WebcastHosted by: Nikhil Karthik
With the first detection of gravitational waves from a binary system of neutron stars, GW170817, a new window was opened to study the properties of matter at and above nuclear-saturation density. Reaching densities a few times that of nuclear matter and temperatures up to 100 MeV, such mergers represent potential sites for a phase transition from confined hadronic to deconfined quark matter. While for GW170817 the postmerger signal could not be detected, such a signal will be a powerful observable in the near future. In this seminar I will present the possible scenarios of how a phase transition to quark-gluon plasma can take place in the postmerger phase of a binary neutron star merger. I will focus on the most recently explored scenario of a so-called ``delayed phase transition'', where the merger remnant transitions from a purely hadronic hypermassive neutron star to a meta-stable hypermassive hybrid star with a dense quark core. This process promises to yield the strongest signature in the gravitational-wave signal for the production of quark matter in the present Universe. Bluejeans link: https://bnl.bluejeans.com/726276981
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Particle Physics Seminar
"Direct CP violation and the Delta I=1/2 rule in K to pi pi decay from the Standard Model"
Presented by Christopher Kelly, BNL
Thursday, June 25, 2020, 3 pm
WebcastHosted by: Viviana Cavaliere
I discuss our recent publication [arXiv:2004.09440] of a lattice QCD calculation of the ΔI=1/2, K→ππ decay amplitude A0 and ?′, the measure of direct CP-violation in K→ππ decay. This quantity is highly sensitive to new sources of CP violation that might help to explain the matter/antimatter asymmetry in the observable Universe. This calculation dramatically improves on our 2015 results [Phys.Rev.Lett. 115 (2015) 21, 212001], including nearly four times the statistics and numerous technical improvements allowing us to more reliably isolate the ππ ground-state and more accurately relate the lattice operators to those defined in the Standard Model. Join Zoom Meeting https://cern.zoom.us/j/94462510754?pwd=Ri9ZUFRIaFFnMFFEMThPeDFzUFJiUT09 Meeting ID: 944 6251 0754 Password: 540367 One tap mobile +41432107042,,94462510754# Switzerland +41432107108,,94462510754# Switzerland Dial by your location +41 43 210 70 42 Switzerland +41 43 210 71 08 Switzerland +41 31 528 09 88 Switzerland +33 1 7037 9729 France +33 7 5678 4048 France +33 1 7037 2246 France Meeting ID: 944 6251 0754 Find your local number: https://cern.zoom.us/u/a8kjRRik8 Join by SIP 94462510754@188.184.85.92 94462510754@188.184.89.188 Join by H.323 188.184.85.92 188.184.89.188 Meeting ID: 944 6251 0754 Password: 540367
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RIKEN Seminar
"Nonperturbative quark-flavor breaking at chiral crossover criticality in hot QCD"
Presented by Mamiya Kawaguchi, Fudan University
Thursday, June 25, 2020, 9 am
WebcastHosted by: Akio Tomiya
We discuss the violation of quark-flavor symmetry at high temperatures, induced from axial anomaly and nonperturbative thermal loop corrections. To perform the nonperturbative analysis, we employ a three-flavor linear-sigma model based on the Cornwall-Jackiw-Tomboulis formalism, in which the flavor breaking induced by the axial anomaly plays a significant role in the light scalar meson spectrum and the vacuum structure of the chiral symmetry. In this talk, we will show the flavor breaking effects on the quark condensates and the meson spectroscopy. The critical flavor violation in the topological susceptibility will be also presented. BJ link: https://bluejeans.com/871723105
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HET Seminar
"Axion like particles at Kaon experiments"
Presented by Stefania Gori, University of Chicago
Wednesday, June 24, 2020, 2:30 pm
WebcastHosted by: Peter Denton
The two Kaon factories, KOTO and NA62, are at the cutting edge of the intensity frontier, with an unprecedented number of long lived and charged Kaons being measured and analyzed. These experiments have a unique opportunity to search for dark sectors. In this seminar, I will explore the complementarity of NA62 and KOTO in probing axion-like-particle (ALP) models, where the ALP is produced from Kaon decays. I will highlight theoretical progress in the calculation of the rates for K -> pi ALP, and possible ways to violate the Grossman-Nir bound that relates K^+ and K_L decays. I will also propose possible new experimental searches that can be performed in the future by the two collaborations, and compare their reach with the reach of other high intensity experiments. Finally, I will also discuss possible models that address the current KOTO anomaly.
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Physics Department Summer Lectures 2020
"Standard Model: Necessary but not Sufficient"
Presented by Hooman Davoudiasl, BNL
Tuesday, June 23, 2020, 12 pm
WebcastHosted by: Mary Bishai
Although the Standard Model of particle physics, in conjunction with General Relativity, explains a wide range of physical phenomena, there are good reasons to believe that it does not represent a complete description of Nature. In this lecture, we will introduce the Standard Model and discuss some of its empirical and conceptual shortcomings. Some of the ideas that have been proposed to address these open questions will also be briefly discussed.
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Nuclear Physics Seminar
"Recent STAR SPIN results I"
Presented by Zhanwen Zhu and Maria Zurek, Shandong University/Lawrence Berkeley National Laboratory
Tuesday, June 23, 2020, 11 am
WebcastHosted by: Rongrong Ma
Measurement of transverse single spin asymmetries at forward rapidities by the STAR experiment at √s = 200 and 500 GeV Zhanwen Zhu, Shandong University We present recent results of transverse single spin asymmetries (TSSA) for neutral pions using the Forward Meson Spectrometer at STAR at center of mass energies of 200 and 500 GeV in proton-proton collision. In order to separate the contribution of initial and final state effects at both energies, we also measured for the electromagnetic jet TSSA and the Collins asymmetry for neutral pions inside the electromagnetic jet. These results together provide rich information to understand the origin of neutral pion TSSA. Longitudinal double-spin asymmetries for inclusive jets produced in √s = 200 GeV proton-proton collisions Maria Zurek, Lawrence Berkeley National Laboratory STAR measures double-spin asymmetries ALL in longitudinally polarized proton-proton collisions to determine the gluon helicity distribution ?G(x,Q2). Previously published inclusive jet results based on √s = 200 GeV data collected in 2009 provided first evidence for positive gluon polarization for a momentum fraction x > 0.05 at a hard perturbative scale Q2 = 10 GeV2. This talk will present new preliminary results from 2015 data with an approximately twice larger figure of merit and correspondingly better precision.
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virtual NT/RIKEN seminar
"Prompt, pre-equilibrium, and thermal photons in relativistic nuclear collisions"
Presented by Akihiko Monnai, JWU Tokyo
Friday, June 19, 2020, 9 am
WebcastHosted by: Nikhil Karthik
The direct photon emission model in relativistic nuclear colliders has been improved in recent years for reducing the discrepancy between theoretical estimations and experimental data and for understanding the properties of the QCD matter. In this talk, the contribution of pre-equilibrium photons are investigated in addition to those of prompt and thermal photons in the framework of a relativistic hydrodynamic model. The numerical simulations at an LHC energy suggest that the pre-equilibrium photons may be relevant at intermediate transverse momentum near the saturation momentum scale, increasing particle spectra and reducing elliptic flow of direct photons. Bluejeans link: https://bnl.bluejeans.com/726276981
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Particle Physics Seminar
"CUORE, CUPID, and the Nature of Neutrino Mass"
Presented by Dr Pranava Teja Surukuchi, Yale University
Thursday, June 18, 2020, 3 pm
WebcastHosted by: Hanyu Wei
The nature of neutrino masses is one of most important open questions in particle physics and has implications of physics beyond the standard model that could hint towards the observed particle-antiparticle asymmetry in the universe. Neutrinoless double-beta decay (0ννβ) is a very rare, hypothesized nuclear process, and is the only practical mechanism that could demonstrate if neutrinos have a Majorana nature. The Cryogenic Underground Observatory for Rare Events (CUORE) located at Laboratori Nazionali del Gran Sasso (LNGS) in Italy is the first ton-scale bolometer experiment that searches for neutrinoless double-beta decay in 130Te. CUORE started collecting data in 2017, and after operational upgrades in 2018, is stably operating with a current exposure of 724.3 kg-yr, with the aim of reaching 5 yr of live time. Using an exposure of 372.5 kg-yr, CUORE set a lower limit of 3.2×1025 yr (90% C.I) on the half-life of 130Te. In this talk, recent results from the latest CUORE analysis campaign will discussed. The current status of CUPID (CUORE Upgrade with Particle IDentification), the proposed experimental upgrade to CUORE, will also be discussed. ZOOM connection: https://fnal.zoom.us/j/98257631764?pwd=MisxZHErTHJBemVsckJFU1VMWWQxQT09 Meeting ID: 982 5763 1764 Password: 493303
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Condensed-Matter Physics & Materials Science Seminar
"Nonequilibrium Dynamics of Collective Excitations in Quantum Materials"
Presented by Edoardo Baldini, Massachusetts Institute of Technology
Thursday, June 18, 2020, 11 am
https://bluejeans.com/956965585Hosted by: Mark Dean
Revealing the dynamics of collective excitations in strongly correlated electron systems is a subject of pivotal importance, as collectivity lies at the origin of several cooperative phenomena that cause profound transformations, instabilities, and phase transitions. In this talk, I will discuss the dynamics of collective excitations (e.g., excitons, magnons, phonons) from the perspective of ultrafast science [1-3]. In particular, I will focus on the role that specific collective excitations play in the formation of hidden phases of matter, i.e. phases that do not have counterparts in the equilibrium phase diagrams of quantum materials. As an example, I will describe our recent discovery of a transient antiferromagnetic metallic phase in a prototypical layered Mott insulator [4]. We observed this phase upon photoexciting a sub-Mott gap exciton-magnon mode, an exotic state of bound electron-hole pairs dressed with the spin degree of freedom [5]. Driving this peculiar exciton also allowed us to realize the coherent control of the underlying antiferromagnetic order for tens of picoseconds, a feature that can lead to the development of novel all-optical magnonic devices. [1] E. Baldini, Nonequilibrium Dynamics of Collective Excitations in Quantum Materials, Springer (2018) [2] E. Baldini*, C. A. Belvin* et al., Nat. Phys. 16, 541-545 (2020) [3] X. Li et al., Science 364, 1079-1082 (2019) [4] C. A. Belvin*, E. Baldini* et al., in review (2020) [5] S. Kang et al., Nature, in press (2020) https://bluejeans.com/956965585
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RIKEN Seminar
"Deep learning black hole metrics from shear viscosity"
Presented by Prof. Shao-Feng Wu, Hanghai University, Yangzhou University
Thursday, June 18, 2020, 9 am
https://bluejeans.com/871723105Hosted by: Nikhil Karthik
Based on the AdS/CFT correspondence, we build up a simple deep neural network to learn the black-hole metrics from the complex frequency-dependent shear viscosity. The network architecture provides a discretized representation of the holographic renormalization group flow of the shear viscosity and is applicable for a large class of strongly coupled field theories. Given the existence of the horizon and guided by the smoothness of spacetimes, we show that the Schwarzschild and Reissner-Nordstrom metrics can be learned accurately. Moreover, we illustrate that the generalization ability of the deep neural network can be excellent, which indicates that using the black hole spacetime as a hidden data structure, a wide spectrum of the shear viscosity can be generated from a narrow frequency range. Our work might not only suggest a data-driven way to study holographic transports, but also shed new light on the emergence mechanism of black hole spacetimes from field theories.
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HET Seminar
"Catching scalar singlets at colliders"
Presented by Matthias Schlaffer, University of Chicago
Wednesday, June 17, 2020, 2:30 pm
WebcastHosted by: Peter Denton
Scalar extensions of the Standard Model provide simple yet phenomenologically rich models for BSM physics that can be looked for at current and future colliders. In my talk I will focus on the renormalizable scalar singlet extension and the relaxion as two benchmark models. Using these benchmarks I will discuss the various strategies needed at the LHC and future colliders to explore their vast parameter space. In particular I will discuss direct search strategies with prompt, displaced, and invisible signatures as well as indirect searches. https://bluejeans.com/767813754
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Nuclear Physics Seminar
"Machine learning based reconstruction of jet transverse momentum in ALICE"
Presented by Hannah Bossi, Yale
Tuesday, June 16, 2020, 11 am
https://bluejeans.com/165700359.Hosted by: Alba Soto Ontoso
Jets in heavy-ion collisions are expected to lose energy through strong interactions with the QGP medium, a phenomena referred to as jet quenching. Experimental observations of jet quenching through observables such as the nuclear modification factor ($R_{\rm AA}$) rely on the precise reconstruction of jet transverse momentum ($p_{\rm T}$). However, jet $p_{\rm T}$ reconstruction is made difficult in heavy-ion collisions due to the large fluctuating background from the underlying event. One common treatment of this background is to perform a pedestal subtraction of the event-averaged momentum density. While this method effectively corrects for the average background, it does not account for region-to-region fluctuations. A novel method to correct the jet $p_{\rm T}$ using machine learning (ML) techniques will be presented. This method utilizes ML techniques to reconstruct the jet $p_{\rm T}$ from jet parameters, including the constituents of the jet. With an ML-based correction, residual fluctuations are reduced, allowing for measurements of the nuclear modification factor at lower $p_{\rm T}$ and larger jet radii (\textit{R}) than previously possible in ALICE. Extending measurements to these regions could help disentangle competing mechanisms of jet energy loss and the recovery of said energy due to the response of the medium. Studies that investigate and estimate the potential fragmentation bias of this ML approach will also be presented. Keeping such studies in mind, comparisons to models will be shown, with the aim of constraining such models at the previously unexplored region of lower $p_{\rm T}$.
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virtual NT/RIKEN seminar
"The quest for precision across scales"
Presented by Gregory Soyez, IPhT
Friday, June 12, 2020, 9 am
WebcastHosted by: Nikhil Karthik
Monte Carlo event generators are among the most used tools in high-energy physics today. As an introduction, I will explain what is their role in modern collider phenomenology. The talk will focus on a central part of Monte Carlo generators, the parton shower, which essentially covers all the scales between the hard scale of the collision and the non-perturbative scale. I will describe how typical parton-shower algorithms are built. I will then report on a recent work (arXiv:2020:11114) where we introduced a new set of parton showers aimed at achieving an unprecedented (logarithmic) accuracy. https://bnl.bluejeans.com/726276981
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Particle Physics Seminar
"Stop(Zh) Neural Networks! A case study in 3rd generation SUSY searches using Machine Learning"
Presented by Gabriele D'Amen, BNL
Thursday, June 11, 2020, 3 pm
WebcastHosted by: Viviana Cavaliere
The widespread use of Machine Learning techniques in the high energy physics community is driving the creation of tools to simplify the implementation of Neural Network methods in a wide variety of analyses. We have developed an artificial neural network framework (HTag) to identify bb pairs coming from the decay of Higgs bosons in events with large jet multiplicities. The use of HTag is expected to improve reconstruction efficiency in a wide kinematic region and to reduce invariant mass bias with respect to traditional reconstruction methods. Information reconstructed with HTag has been used in a search for direct top squark pair production in events with missing transverse momentum plus either a pair of jets consistent with the Standard Model Higgs boson decay to b-quarks or a same-flavour opposite-sign dilepton pair with invariant mass consistent with a Z boson. The analysis is performed using the proton-proton collision data at √s=13 TeV collected by the ATLAS experiment during the LHC Run-2, corresponding to an integrated luminosity of 139 fb−1. No excess is observed in the data with respect to the Standard Model predictions. Zoom information: https://cern.zoom.us/j/97420636116?pwd=N083bERNQ3d4RTBFS0hXU1M5Vytvdz09 Meeting ID 974 2063 6116 Meeting Password 040606
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RIKEN Seminar
"Transport and hydrodynamics in the chiral limit"
Presented by Alexander Soloviev, Stony Brook University
Thursday, June 11, 2020, 9 am
WebcastHosted by: Yuta Kikuchi
I will discuss the evolution of hydrodynamic fluctuations for QCD matter below T_c in the chiral limit. The theoretical description is ordinary hydrodynamics at long distances and superfluid-like at short distances. The latter is represented by pions (the Goldstone modes), reflecting the broken SU(2)_L x SU(2)_R symmetry. The superfluid degrees of freedom contribute to the transport coefficients of the ordinary theory at long distances. This determines the leading dependence of some transport parameters of QCD on the pion mass. I will make some comments on the predictions of this computation near the O(4) critical point. https://bluejeans.com/724325293
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HET Seminar
"Chat"
Wednesday, June 10, 2020, 2:30 pm
WebcastThis week's seminar will be replaced with a casual conversation motivated by: https://www.particlesforjustice.org. There is no scheduled content, just a place for interested parties to discuss racial issues. https://bluejeans.com/767813754
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HET Seminar: SPECIAL DAY
"The Higgs Portal: Constraints on New Physics"
Presented by Milada Mühlleitner, KIT
Tuesday, June 9, 2020, 2:30 pm
WebcastHosted by: Peter Denton
One of the main goals of the LHC is the search for New Physics. So far, the only new particle that has been discovered at the LHC is the Higgs boson. There is no direct sign of any particle beyond the Standard Model (SM) so far. In view of this situation we have to ask ourselves how we can exploit the Higgs sector to search indirectly for New Physics. I will discuss the role that the effective field theory (EFT) approach plays in this context. EFT is a possibility to smoothly depart from the SM and parametrize our ignorance about NP by assuming that NP appears at some high energy scale. I will focus on the top-Higgs interface and Higgs pair production and discuss the role of global fits. Since EFT assumes NP to be heavy, the combined analysis within EFT and specific UV-complete models is important in order not to miss any sign of NP. I will hence also present some specific examples of Higgs pair production in UV-complete models. https://bluejeans.com/767813754
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Nuclear Physics Seminar
"Highlights of the charge separation measurements using the $R_{\Psi_m}(\Delta S)$ correlator implications for the chiral magnetic effect"
Presented by Niseem Abdelrahman, Stony Brook University
Tuesday, June 9, 2020, 11 am
WebcastHosted by: Jiangyong Jia
The study of anomalous transport in QGP can give fundamental insight not only on the complex interplay of chiral symmetry restoration, axial anomaly, and gluon topology but also on the evolution of magnetic fields in the early Universe. A primary anomalous process predicted to occur in the magnetized QGP, created in RHIC collisions is the chiral magnetic effect (CME). In this talk, I will discuss the rudiments and the results from studies involving the use of a new charge sensitive correlator $R_{\Psi_m}(\Delta S)$, designed to detect and characterize the CME. The experimental measurements performed with the $R_{\Psi_m}(\Delta S)$ correlator, show the expected patterns for background-driven charge separation for the measurements relative to $\Psi_3$ and those relative to $\Psi_2$ for the $p$($d$)+Au systems. By contrast, the Au+Au measurements relative to $\Psi_2$, show event-shape-independent $R_{\Psi_2}(\Delta S)$ distributions consistent with a CME-driven charge separation, quantified by widths having an inverse relationship to the Fourier dipole coefficient $\tilde{a}_1$, which evaluates the CME. The $R_{\Psi_2}(\Delta S)$ results and their dependencies on the system-size, centrality, and event-shape, as well as the future use of the correlator, will be discussed in details. https://bluejeans.com/165700359.
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HET Lunch Seminar
"Gravitational Interactions and Neutrino Masses"
Presented by Hooman Davoudiasl, BNL
Friday, June 5, 2020, 12:15 pm
WebcastHosted by: Peter Denton
We describe a scenario where the smallness of neutrino masses is related to a global symmetry that is only violated by quantum gravitational effects. Here, the coupling of neutrinos to gauge singlet right-handed fermions is attributed to symmetry preserving gravitational operators suppressed by the Planck mass. The proposed scenario leads to axion particles that decay into neutrinos, which could be probed through cosmological measurements and may help explain the Hubble parameter tension. The scenario could potentially provide axion dark matter candidates. https://bluejeans.com/507765681
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RIKEN Seminar
"From quarks to nuclei: machine learning the structure of matter"
Presented by Phiala Shanahan, MIT
Thursday, June 4, 2020, 12 pm
WebcastHosted by: Akio Tomiya
I will discuss the status and future of lattice Quantum Chromodynamics (QCD) calculations for nuclear physics. With advances in supercomputing, we are beginning to quantitatively understand nuclear structure and interactions directly from the fundamental quark and gluon degrees of freedom of the Standard Model. Recent studies provide insight into the neutrino-nucleus interactions relevant to long-baseline neutrino experiments, double beta decay, and nuclear sigma terms needed for theory predictions of dark matter cross-sections at underground detectors. The rapid progress in this field has been possible because of new algorithms but challenges still remain to reach the large nuclei used in many of these experiments. Recently, machine learning tools have been shown to provide a potentially revolutionary way to address these challenges and allow a Standard Model understanding of the physics of nuclei. Bluejeans link: https://bluejeans.com/806818825
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Particle Physics Seminar
"Dijet resonance search with weak supervision using √s = 13 TeV pp collisions in the ATLAS detector"
Presented by Aviv Cukierman, SLAC
Thursday, May 28, 2020, 3 pm
WebcastHosted by: Viviana Cavaliere
We present a search for resonant new physics using a machine learning anomaly detection procedure that does not rely on a signal model hypothesis. Weakly supervised learning is used to train classifiers directly on data to enhance potential signals. The targeted topology is dijet events and the features used for machine learning are the masses of the two jets. The resulting analysis is essentially a 3-dimensional search A → BC, for mA ∼ O(TeV), mB,mC ∼ O(100 GeV) and B,C → large-radius jet, without paying a penalty associated with a large trials factor in the scan of the masses of the two jets. The full Run 2 √s = 13 TeV pp collision dataset of 139 fb−1 recorded by the ATLAS detector at the Large Hadron Collider is used for the search. There is no significant evidence for a localized excess in the dijet invariant mass spectrum between 1.8 and and 8.2 TeV. Cross section limits for narrow-width A, B, and C particles vary with mA, mB, and mC. For example, when mA = 3 TeV and mB ≥ 200 GeV, a production cross section between 1 and 5 fb is excluded, depending on mC. These limits are up to 20 times more sensitive than those obtained by the inclusive dijet search. Details for connection: on Zoom: Direct link https://cern.zoom.us/j/99990161911?pwd=Wk5xVzhzSTd4MXV2ZHllMHl0TDVoUT09 Meeting ID 999 9016 1911 Password: 893053
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Virtual BNL RIKEN Seminar
"Sign Problem in Monte Carlo Simulations and the Tempered Lefschetz Thimble Method"
Presented by Masafumi Fukuma, Kyoto U.
Thursday, May 28, 2020, 9 am
WebcastHosted by: Akio Tomiya
The tempered Lefschetz thimble method (TLTM) [arXiv:1703.00861] is a parallel-tempering algorithm towards solving the numerical sign problem. It uses the deformation parameter of integration surface (the flow time of the antiholomorphic gradient flow) as a tempering parameter, and is expected to tame both the sign and ergodicity problems simultaneously that exist intrinsically in thimble methods. In this talk, I explain the basics of TLTM, and apply the method to various problems, including the quantum Monte Carlo simulation of the Hubbard model away from half filling and the chiral random matrix models with finite temperature and finite chemical potential. This talk is based on collaboration with Nobuyuki Matsumoto and Naoya Umeda [arXiv: 1703.00861, 1906.04243, 1912.13303]. Bluejeans Link: https://bluejeans.com/871723105
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virtual NT/RIKEN seminar
"Why is chemical freezeout at the chiral cross over temperature?"
Presented by Sourendu Gupta, TIFR Mumbai
Friday, May 22, 2020, 9 am
WebcastHosted by: Nikhil Karthik
Studies of the composition of the fireball produced in very high energy heavy-ion collisions show that the composition is that of an equilibrium gas of hadrons at a temperature of about 155 MeV, and zero chemical potential. At the same time, lattice computations show that the chiral cross over of QCD occurs at a temperature of about 155 MeV. The composition of the fireball is a question of the dynamics of hadron reactions, whereas the location of a cross over is a question about the equilibrium free energy density. I describe a computation which shows why they coincide. Bluejeans link: https://bnl.bluejeans.com/726276981
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RIKEN Seminar
"From anomalous correlations to dark matter: the effects of higher topological charge"
Presented by Fabian Rennecke, BNL
Thursday, May 21, 2020, 9 am
Bluejeans link: https://bluejeans.com/651508428Hosted by: Yuta Kikuchi
Topological gauge field configurations play an important role in the phenomenology of QCD. The axial anomaly is inextricably linked to topological effects. They give rise to anomalous meson masses, affect the order of the chiral phase transition, and lead to the chiral magnetic effect which is relevant for condensed matter and heavy-ion physics. On the flip side, topological gauge field configurations can also give rise to CP violating effects in QCD. A potential resolution of this strong CP problem involves a new particle, the axion. Incidentally, axions are also viable dark matter candidates and their properties are largely determined by the distribution of topological charge in QCD. At high energies in the deconfined regime, the topological structure of QCD is well described by a dilute gas of instantons. In this regime all the effects mentioned above are typically studied based on instantons of unit topological charge. As discussed in this talk, there are also effects uniquely related to instantons of higher topological charge. On the one hand, they give rise to higher-order anomalous quark correlations which manifest themselves in anomalous hadronic interactions. On the other hand, they modify the distribution of topological charge. This, in turn, affects the properties of axions and can lead to a topological mechanism to increase the amount of axion dark matter.
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HET Seminar
"Probing High-Energy Light Dark Matter with IceCube"
Presented by Meng-Ru Wu, Institute of Physics, Academia Sinica
Wednesday, May 20, 2020, 10 am
https://bluejeans.com/767813754Hosted by: Peter Denton
The direct detection of particle dark matter through its scattering with nucleons is of fundamental importance to understand the nature of dark matter. In our recent work 2004.03161, we proposed that the high-energy neutrino detectors like IceCube can be used to uniquely probe the dark matter — nucleon cross-section for high-energy DM of ~ PeV, up-scattered by the high-energy cosmic rays. We derive for the first time constraints on the dark matter — nucleon cross-section down to ~ 10^-32 cm^2 at this energy scale for sub-GeV dark matter. Such independent probe at energy exceeding other existing direct detection experiments can provide useful insights complementary to other searches.
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Particle Physics Seminar
"First Detection of Coherent Elastic Neutrino-Nucleus Scattering on Argon"
Presented by Dr Jacob Daughhetee, University of Tennessee
Tuesday, May 19, 2020, 3 pm
WebcastHosted by: Hanyu Wei
In 2017, the COHERENT collaboration made the first observation of coherent elastic neutrino-nucleus scattering (CEvNS) using a 14.6 kg CsI scintillating crystal detector located at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. In addition to neutrons, the 1.4 MW pulsed (60 Hz) proton beam at the SNS produces charged pions which subsequently decay to yield a large neutrino flux with a well-known energy spectrum and time structure. COHERENT employs a suite of detectors at the SNS to search for CEvNS in different target nuclei and to measure potential backgrounds. This multi-target program allows for testing of Standard Model predictions for CEvNS as well as for verifying the N^2 -dependence of the cross section of this interaction. CENNS-10, a 24 kg liquid argon scintillation detector, has been actively taking data at the SNS since the spring of 2017. This talk will detail the methods and results of a search for and detection of CEvNS in CENNS-10 data. Zoom link is https://fnal.zoom.us/j/99418285608?pwd=T05PMFcyZ1ZjY2hscU9zTzNsUTFTQT09
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Nuclear Physics Seminar
"New Results on Short-Range Correlations from 48 GeV/c 12C+p Reactions - from the Nuclotron to FAIR and the"
Presented by Prof. Or Hen, MIT
Tuesday, May 19, 2020, 11 am
WebcastHosted by: Alba Soto Ontoso
New results from a measurement of 12C+p reactions performed at the JINR in Dubna with a 48 GeV/c Carbon-12 beam demonstrate the feasibility of accessing properties of short-range correlated nucleons in nuclei with hadronic probes and by using inverse kinematics. We extract the ground-state distributions of single nucleons and correlated nucleon pairs (SRC) in quasi-free kinematics in an exclusive measurement by detecting the two scattered protons at large angles in coincidence with an intact heavy fragment. The post-selection of heavy fragments is shown to suppress the otherwise large contributions from final-state interactions. This allowed for the first time to select and study properties of correlated nucleon pairs in inverse kinematics. This new measurement showcases a new ability to relate short-distance nuclear and partonic dynamics via fragment tagging at the EIC and to study the short-distance structure of short-lived neutron-rich nuclei at the forthcoming FRIB and FAIR facilities. Bluejeans link is https://bluejeans.com/165700359.
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virtual NT/RIKEN seminar
"Quantum criticality in fermion-bag inspired Hamiltonian lattice field theories"
Presented by Emilie Huffman, Perimeter Institute
Friday, May 15, 2020, 11 am
WebcastHosted by: Nikhil Karthik
Motivated by the fermion bag approach—a quantum Monte Carlo approach that takes advantage of grouped local degrees of freedom—we consider a new class of Hamiltonian lattice field theories that can help us study fermionic quantum critical points. We construct the partition function of a lattice Hamiltonian in 2+1 dimensions in discrete time, with a temporal lattice spacing \varepsilon. When \varepsilon \rightarrow 0, we obtain the partition function of the original lattice Hamiltonian. But when \varepsilon = 1, we obtain a new type of space-time lattice field theory which treats space and time differently, but still lacks fermion doubling in the time dimension, in contrast to Lagrangian lattice field theories. Here we show that both continuous-time and discrete-time lattice field theories derived from the t-V model have a fermionic quantum critical point with critical exponents that match within errors. The fermion bag algorithms run relatively faster on the discrete-time model and allow us to compute quantities even on 100^3 lattices near the quantum critical point. Bluejeans link: https://bnl.bluejeans.com/726276981
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HET Seminar
"Dark Sector Decays in the DUNE Multipurpose Near Detector"
Presented by Kevin Kelly, FNAL
Wednesday, May 13, 2020, 2:30 pm
WebcastHosted by: Peter Denton
The upcoming Deep Underground Neutrino Experiment will enable precision measurements of physics in the neutrino sector, a long-standing goal since the phenomenon of neutrino oscillations was observed. In order to meet its ambitious goals, DUNE will consist of argon-based detectors: a 40 kiloton liquid argon far detector, and several components at its near detector site at Fermilab. Included in this near detector plan is the Multi-Purpose Detector, a gaseous argon detector surrounded by an electromagnetic calorimeter, all situated within a magnetic field. I will demonstrate how this MPD can be used for physics beyond neutrino oscillations, specifically, searching for the decays of new particles that could be associated with dark matter. The MPD is able to improve current experimental limits in searches for Dark Photons, Dark Higgs Bosons, Leptophilic gauge bosons, and Heavy Neutral Leptons. I will also show an intriguing possibility if a Heavy Neutral Lepton is discovered by DUNE, where the possibility of determining whether such a new particle is a Dirac or Majorana fermion is possible. Bluejeans link : https://bluejeans.com/767813754
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virtual NT/RIKEN seminar
"Open QFTs from holography"
Presented by R. Loganayagam, ICTS, Bangalore
Friday, May 8, 2020, 9 am
WebcastHosted by: Nikhil Karthik
In this talk, I will outline a formalism to study open quantum field theories using holographic methods. More precisely, I will consider a quantum field theory (the system) coupled to a holographic field theory at finite temperature (the environment). The aim here is to integrate out the holographic environment with an aim of obtaining an effective dynamics for the resulting open quantum field theory. This is done using semiclassical gravitational Schwinger-Keldysh saddle geometries obtained by complexifying black hole spacetimes. In addition to shedding light on open quantum systems coupled to strongly correlated thermal environments, these results also provide a principled computation of Schwinger-Keldysh observables in gravity and holography. In particular, these influence functionals capture both the dissipative physics of black hole quasinormal modes, as well as that of the fluctuations encoded in outgoing Hawking quanta, and interactions between them. This talk will be based on https://arxiv.org/abs/2004.02888 Bluejeans link: https://bnl.bluejeans.com/726276981
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Condensed-Matter Physics & Materials Science Seminar
"Towards Novel Quantum Materials: Design, Synthesis and Characterizations"
Presented by Ruidan Zhong, Princeton University
Thursday, May 7, 2020, 1:30 pm
Zoom CMPMSD SeminarHosted by: Qiang Li
Quantum materials are materials where the extraordinary effects of quantum mechanics give rise to exotic and often incredible properties. To understand their basic behavior if we are to enable optimization for a specific purpose, discovering novel quantum materials is a primary task for scientists in the field of condensed matter physics and materials science. In this seminar, research strategies toward novel quantum materials in experiment will be introduced from the perspective of chemistry, materials science and physics. Such research process leads to fruitful results, and two recent discovered candidates of quantum spin liquid (QSL) will be presented as an example. The first candidate is a geometric frustrated magnet, Na2BaCo(PO4)2, which is structurally perfect without intrinsic disorder. Experimental results, including magnetization, specific heat, and neutron scattering, have indicated that this compound is an ideal QSL candidate. The second compound, BaCo2(AsO4)2, are believed to be a Kitaev QSL candidate. This is the first time that Kitaev physics are proposed to be realized in 3d-transition-metal honeycomb in experiment. Non-Kitaev interactions can be fully suppressed by low field, yielding nonmagnetic ground state and many other similarities with the well-studied Kitaev QSL α-RuCl3. https://us02web.zoom.us/j/89625989696
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HET Lunch Seminar
"Flavorful Higgs Physics from the MeV to TeV scale"
Presented by Samuel Homiller, YITP, Stony Brook
Friday, May 1, 2020, 12:15 pm
WebcastHosted by: Peter Denton
I will discuss two related opportunities for searching for new physics with flavorful couplings to the Standard Model, both intimately related to the Higgs boson. First, I will discuss the recently observed events at the KOTO experiment, and how they could be explained by Higgs portal extensions to the Standard Model. I will then discuss the interplay of BSM flavor physics and the Higgs more generally, with an emphasis on the usual theoretical biases about how new physics may couple to the Standard Model. This will lead me to an introduction to the Spontaneous Flavor Violation (SFV) framework, which avoids some of these biases while allowing for large couplings between new physics and any SM quark generation in a robust and UV complete way. In the context of extended Higgs sectors, the SFV Ansatz leads to strikingly different phenomenology compared to typical models at both the energy and intensity frontiers, and provides strong motivation for developing new techniques such as light quark taggers at colliders. Bluejeans link:https://bluejeans.com/507765681
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virtual NT/RIKEN seminar
"Transverse momentum distributions: predictive power and flavor structure"
Presented by Andrea Signori, Jlab
Friday, May 1, 2020, 9 am
WebcastHosted by: Nikhil Karthik
Transverse momentum distributions (TMDs) allow one to map the hadronic structure in a three-dimensional momentum space, exploring all the possible spin and momentum correlations between a hadron and its elementary constituents. I will discuss their predictive power as a function of the kinematics and, in particular, I will show that the flavor structure of the TMDs can have an impact on the determination of the W boson mass at the Large Hadron Collider, providing a new connection between 3D hadron tomography and high-energy physics. Bluejeans link: https://bnl.bluejeans.com/726276981
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HET Seminar
"Lepton flavour violating decays into axion-like particles"
Presented by Lorenzo Calibbi, Nankai University
Wednesday, April 29, 2020, 10 am
WebcastHosted by: Peter Denton
Pseudo Nambu-Goldstone bosons (also known as axion-like particles) with flavour-violating couplings to the Standard Model (SM) fermions are a rather generic consequence of spontaneously-broken global U(1) symmetries, e.g. if the SM fermions carry flavour non-universal charges. A possible consequence is the occurrence of flavour-violating decays of hadrons and leptons into light axion-like particles. These exotic signatures are a powerful probe of such kind of scenarios. I will discuss the phenomenological consequences at future experiments, focusing in particular on searches for lepton flavour violation, and compare their sensitivity to the symmetry-breaking scale with bounds from stellar evolution. Bluejeans link is https://bluejeans.com/767813754.
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HET Lunch Seminar
"Validity of SMEFT studies of VH and VV Production at NLO"
Presented by Samuel Lane, University of Kansas
Friday, April 24, 2020, 12:15 pm
https://bluejeans.com/507765681Hosted by: Peter Denton
The production of W±H, ZH, W+W−, and W±Z pairs probes non-Standard-Model interactions of quarks, gauge bosons, and the Higgs boson. New effects can be parameterized in terms of an effective field theory (EFT) where the Lagrangian is expanded in terms of higher-dimension operators suppressed by increasing powers of a high scale Λ. We examine the importance of including next-to-leading-order QCD corrections in global fits to the coefficients of the EFT. The numerical implications on the fits due to different approaches to enforcing the validity of the EFT are quantified. We pay particular attention to the dependence of the fits on the expansion in 1/Λ2 since the differences between results calculated at O(1/Λ2) and O(1/Λ4) may give insight into the possible significance of dimension-8 effects
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virtual NT/RIKEN seminar
"3D Tomography of Parton Motion inside Hadrons"
Presented by Jianwei Qiu, Jefferson Lab
Friday, April 24, 2020, 9 am
Bluejeans: https://bnl.bluejeans.com/726276981Hosted by: Nikhil Karthik
The TMD Topical Collaboration, funded by the DOE Office of Nuclear Physics, was formed by pulling together expertise in QCD theory, phenomenology and lattice QCD from 10 universities and 4 national labs to address the challenge to develop new theoretical and phenomenological tools that are urgently needed for precision extraction of 3D tomography of parton motion inside hadrons from current and future data. In this talk, I will briefly summarize the challenge to extract the true parton motion inside a bound hadron once it is broken by the collisions, and how the TMD Collaboration integrates our knowledge in QCD theory, phenomenology and lattice QCD to overcome the challenge.
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HET Seminar
"The Boundary of the SMEFT"
Presented by Grant Remmen, UC Berkeley
Wednesday, April 22, 2020, 2:30 pm
WebcastHosted by: Peter Denton
Hints of new physics are encoded as higher-dimension operators in effective field theory. The couplings of these operators, "dial settings" in the low-energy laws of physics, can be bounded using methods independent of the ultraviolet completion, relying only on principles like causality, unitarity of quantum mechanics, and properties of scattering amplitudes. In this talk, I will show how such infrared consistency techniques can be used to constrain operators in the EFT of the standard model. For quartic bosonic and fermionic operators at mass dimension 8, I will construct the bounds and discuss phenomenological consequences. These constraints give compelling near-term experimental implications for CP and flavor violation as well as collider physics, and provide us with powerful means to test the tenets of quantum field theory itself.
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Virtual NT/RIKEN seminar
"Exploring aspects of QCD from Quantum Link Models"
Presented by Debasish Banerjee, PNNL
Friday, April 17, 2020, 9 am
Bluejeans:https://bnl.bluejeans.com/726276981Hosted by: Nikhil Karthik
QCD has been extensively studied in various regimes and using various methodologies. While the lattice regularized version is the most popular ab-initio version, this approach has problems dealing with dense, as well as non-equilibrium QCD matter. In this talk, I will introduce the so-called Quantum Link Models, which offer a different approach to the problem. We will explore some qualitative aspects of QCD and nuclear physics using these models.
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HET Lunch Seminar
"Electroweak Baryogenesis, Higgs rates and EDMs with dim-6 complex Yukawas"
Presented by Elina Fuchs, University of Chicago
Wednesday, April 15, 2020, 2:30 pm
WebcastHosted by: Peter Denton
Complex dimension-six Yukawa couplings of the Higgs boson to quarks and leptons have interesting implications for collider rates of Higgs production and decay, EDMs and CP violation for electroweak baryogenesis. We explore if there are viable regions fulfilling all of these three complementary constraints, considering real and imaginary dimension-six terms of the tau, muon, top and bottom, each flavor separately and combinations thereof that allow for cancellations in the EDM and an enhancement of the baryogenesis. We find that a complex tau Yukawa can account for the observed baryon asymmetry. Furthermore we highlight that a complex muon Yukawa large enough to account for the observed baryon asymmetry of the universe is allowed by the current bound on the electron EDM, but clearly ruled out by the recent upper bound on the Higgs decay rate to a pair of muons.
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Particle Physics Seminar
"Maximizing the potential of neutrino experiments"
Presented by Philip Rodrigues, University of Oxford
Thursday, April 9, 2020, 3 pm
WebcastHosted by: Chao Zhang
Present and future neutrino experiments will search for CP violation in the lepton sector, detect neutrinos from a galactic supernova, and search for evidence of sterile neutrinos. I will discuss two strands of work aimed at maximizing the success of these experiments: on DUNE, developing the far detector trigger system is vital to achieving the physics goals of the experiment; while on the SBN project, neutrino cross section uncertainties are a major systematic in the sterile neutrino oscillation analysis.
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CSI Q Seminar
"CANCELLED Quantum-driven classical optimization"
Presented by Helmut Katzgraber, Microsoft Research
Wednesday, April 8, 2020, 1:30 pm
Training Room, Bldg 725Hosted by: Layla Hormozi
The advent of the first useful quantum computing devices has resulted in an arms race with classical algorithms on traditional computing hardware. While near-term quantum devices might revolutionize, e.g., optimization and quantum chemistry, tackling many applications will directly depend on either hybrid or purely classical computing techniques. Inspired by these recent exciting developments, a variety of new classical algorithms have emerged. In this talk an overview on quantum inspired methods and their applications is given.
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HET Lunch Seminar
""Physics Opportunities with Potential DUNE Beam Upgrades""
Presented by Mary Bishai (BNL)
Friday, March 27, 2020, 12:15 pm
BluejeansHosted by: Peter Denton
Bluejeans link is https://bluejeans.com/507765681 Bluejeans: You can call in from the US with: tel:+1.888.748.9073 and the meeting ID is 507 765 681.
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Particle Physics Seminar
"Overcoming Neutrino Interaction Mis-modeling with DUNE-PRISM"
Presented by Luke Pickering, Michigan State University
Thursday, March 26, 2020, 3 pm
web castHosted by: George Redlinger
The expected precision of current long-baseline neutrino oscillation experiments (T2K, NOνA) will be limited by uncertainties in neutrino interaction models in addition to sample statistics. The interaction uncertainties will also play a significant role in next-generation experiments (DUNE, Hyper-K), which aim to collect much larger samples of oscillated neutrinos. Without significant advancements in neutrino-nucleus interaction modeling, traditional analyses will be susceptible to biased oscillation measurements. The DUNE-PRISM (Precision Reaction Independent Spectrum Measurement) technique offers a complementary approach to the oscillation analysis methods used by T2K, NOνA, and MINOS. DUNE-PRISM uses direct extrapolation of near detector data to infer oscillation probabilities with significantly less dependence on the validity of neutrino interaction models. This is achieved by combining multiple near detector measurements, each taken with the detector at a different off beam axis position, in order to sample a variety of neutrino energy spectra. This talk will introduce DUNE-PRISM and show how the oscillation parameters extracted using this technique are robust to unknown interaction modeling errors.
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Particle Physics Seminar
"Exploring the neutrino physics with the Deep Underground Neutrino Experiment"
Presented by Jingbo Wang, University of California, Davis
Tuesday, March 24, 2020, 3 pm
WebcastHosted by: Chao Zhang
One of the biggest surprises in particle physics is that the neutrinos have mass, which was discovered by the neutrino oscillation experiments. This fundamental property of neutrinos leads to some new questions. What is the ordering of the neutrino mass states? Do the neutrinos violate the matter/antimatter symmetry? What characteristics does the neutrino mixing matrix have? The Deep Underground Neutrino Experiment (DUNE) will address these questions with the high-precision Liquid Argon Time Projection Chamber (LArTPC) technology. In this talk, I will give a brief overview of neutrino oscillations, then describe DUNE and its physics programs. I will also talk about the Pulsed Neutron Source as an innovative calibration technique for liquid argon TPCs. The precision measurements of the neutrinos will open a window to new physics beyond the standard model. We will discuss the future and prospects of neutrino physics.
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Particle Physics Seminar
"Probing ν interactions for ν physics"
Presented by Adi Ashkenazi, MIT
Friday, March 20, 2020, 10:30 am
web castHosted by: Vladmir Tischenko
The ability of current and next generation accelerator based neutrino oscillation measurements to reach their desired sensitivity requires a high-level of understanding of the neutrino-nucleus interactions. These include precise estimation of the relevant cross sections and the reconstruction of the incident neutrino energy from the measured final state particles. Incomplete understanding of these interactions can skew the reconstructed neutrino spectrum and thereby bias the extraction of fundamental oscillation parameters and searches for new physics. In this talk I will present the first exclusive differential cross section measurement using neutrino-Argon Quasi Elastic like interactions from the MicroBooNE experiment. In addition, using wide phase-space electron scattering data, collected using the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility (JLab), the reconstruction of the incoming lepton energy from the measured final state is being tested. Disagreements with current event generators, used in the analysis of neutrino oscillation measurements, are observed which indicate underestimation of nuclear effects. The impact of these findings on bias in oscillation analyses will be discussed.
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RIKEN Lunch Seminar
"Ioffe time behavior of PDFs and GPDs"
Presented by Abha Rajan, BNL
Thursday, March 12, 2020, 12 pm
Building 510, Room 2-160Hosted 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.
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Physics Colloquium
"A tale told by hard probes in high energy nuclear collisions – from PHENIX to sPHENIX and on toward the EIC"
Presented by Jin Huang, BNL
Tuesday, March 10, 2020, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Bjoern Schenke
Hard probes such as heavy flavor quarks, jets, and virtual and real photons convey valuable information from the heart of high energy nuclear collisions, opening a window into the microscopic nature of QCD matter. These probes have been used to study both hadronic states and also nuclear matter under extreme conditions. In addition, the spin degree of freedom of the colliding proton provides a fresh perspective on the quantum nature of nuclear matter, enabled by the unique capabilities of RHIC. The rareness of hard probes demands detectors capable of high precision and high rate, which in turn drives the design and the innovation of the next generation of nuclear physics collider experiments, such as sPHENIX and future EIC detectors. I will recount a story told by hard probes of nuclear collisions through selected results from PHENIX, the plans for sPHENIX, and the possibilities at the EIC.
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Nuclear Physics Seminar
"Jet quenching tests of the QCD Equation of State"
Presented by Xabier Feal, BNL
Tuesday, March 10, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
We re-analyze the bremsstrahlung problem in a background field consisting of several sources. We explain how these processes can be represented as a sum of diagrams, generally interfering and thus leading to the well known LPM effect. Then we show how these diagrams can be properly resummed at high energies to go beyond the most common approximations in phenomenological analyses to date: the perturbative (GLV), the Gaussian (BDMPS) or the semi-infinite medium (AMY) approximations. Finally we present some QED and QCD results, and show how the improvement is able to cure some of the puzzles found in data, namely the temperature issues in the determination of the QGP color opacity, encoded usually in the transport coefficient, $\hat{q}$. This finding indicates that full resummations are required for a proper extraction of the QCD matter parameters, and may open up an additional handle on the study of the QCD Equation of State.
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RIKEN Lunch Seminar
"Nonperturbative Collins-Soper Kernel from Lattice QCD"
Presented by Yong Zhao, BNL
Thursday, March 5, 2020, 12 pm
Building 510, Room 2-160Hosted 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.
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Particle Physics Seminar
"What is the Higgs boson hiding"
Presented by Caterina Vernieri, SLAC National Accelerator Laboratory
Wednesday, March 4, 2020, 4 pm
Small Seminar Room, Bldg. 510Hosted by: Viviana Cavaliere
The Higgs boson discovery at the LHC marked a historic milestone in the study of fundamental particles and their interactions. Over the last eight years, we have begun measuring its properties, which are essential to build a deep understanding of the Higgs sector of the Standard Model and to potentially uncover new phenomena. The Standard Model is far from being a complete theory of nature and many of its predictions have yet to be tested. In particular, the energy potential of the Higgs boson field, responsible for the electroweak symmetry breaking mechanism, has not yet been measured by any experiment. A measurement of the Higgs boson self-coupling at the LHC would shed light into the actual structure of the potential, whose exact shape can have deep theoretical consequences. This coupling can be accessed directly through the very challenging measurement of Higgs pair production. In this talk the experimental status of the di-Higgs boson production searches and constraints on the self-coupling at the LHC will be presented and the special role played by the decay to b-quark, the largest Higgs branching fraction, and its distinctive signature will be described.
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HET Seminar
"Teaching a Computer to Integrate"
Presented by Christina Gao, Fermilab
Wednesday, March 4, 2020, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Peter Denton
We present a novel integrator based on normalizing flows which can be used to improve the unweighting efficiency of Monte-Carlo event generators for collider physics simulations. In contrast to the machine learning approaches based on surrogate models, our method generates the correct result even if the underlying neural networks are not optimally trained. We exemplify the new strategy using the example of Drell-Yan type processes at the LHC.
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Nuclear Physics Seminar
"Direct Photon Production in Au+Au collisions at 200GeV"
Presented by Wenqing Fan, Stony Brook University
Tuesday, March 3, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
The PHENIX experiment operates as one of the major detectors at the RHIC collider to identify and study Quark Gluon Plasma (QGP). Direct photons have long been considered as unique probes to study properties of QGP due to their small interaction cross section with the collision produced medium, hence carrying direct information of their creation point. Taking advantage of the precise tracking system and high granularity electromagnetic calorimeter, PHENIX has made comprehensive measurements of direct photons across different collision species and a wide range of beam energies. In this talk I will show new measurements with high statistics Au+Au data taken in 2014 at 200GeV using the photon conversions at the silicon vertex detector (VTX). This dataset provides a 10-fold increase in statistics for the measurements of direct photon yields and their anisotropy.
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Particle Physics Seminar
"HUNTER: a search for keV-scale sterile neutrinos using trapped atoms"
Presented by Prof. Peter Meyers
Wednesday, February 26, 2020, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Hanyu Wei
The HUNTER experiment is a search for sterile neutrinos with masses in the 10-300 keV range. The neutrino missing mass will be reconstructed from 131-Cs electron capture decays occurring in a magneto-optically trapped, laser-cooled sample. Reaction-microscope spectrometers will be used to measure the vector momenta of all charged decay products with high solid angle acceptance, and LYSO scintillators read out by silicon photomultiplier arrays detect x-rays, each with sufficient resolution to reconstruct the neutrino missing mass as a peak separated from the near-zero-mass active neutrinos. The stand-alone apparatus to do this has dimensions of a few meters.
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Physics Colloquium
"From actions to answers: flavour physics from lattice gauge theory"
Presented by Peter Boyle, BNL
Tuesday, February 25, 2020, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Hooman Davoudiasl
Lattice gauge theory is a numerical approach to the Feynman path integral, and is the only systematically improvable approach to make theoretical predictions of hadronic properties from the underlying theory of quarks and gluons. I will present theoretical numerical calculations of hadronic properties that represent theoretical input to flavour physics, quark flavour mixing, and standard model CP violation in the Kaon, D and B mesons. These lead to constraints on CKM flavour mixing constants of the standard model, and searches for new physics.
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Nuclear Physics Seminar
"Balance function as a unique probe to the quark gluon plasma: overview and outlook"
Presented by Jin Jin Pan, Wayne State University
Tuesday, February 25, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jiangyong Jia
In relativistic heavy-ion collisions, correlations of hadrons with opposite quantum numbers provide insight into general charge creation mechanisms, the time scales of quark production, collective motion of the Quark Gluon Plasma (QGP), and re-scattering in the hadronic phase. The longitudinal and azimuthal widths of general charge balance functions for charged pion (??±), kaon (??±) and (anti-)proton (??/??¯) are used to examine the two-wave quark production scenario recently proposed to explain quark-antiquark productions within the QGP, which predicts a large increase in up and down quark pairs relative to strange quark pairs around the time of hadronization. Balance function as a function of relative azimuthal angle is a good probe to the diffusion effect, which is a signature of the QGP. In addition, the balance function integrals measure hadron pairing probabilities, which provide a key constraint for hadron productions in models. Furthermore, balance function is also a key observable to study net-proton fluctuations and the Chiral Magnetic Effect (CME). In this talk, I will present a state-of-the-art overview on experimental measurements of balance function by STAR and ALICE, along with an outlook for the future experimental measurements.
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Condensed-Matter Physics & Materials Science Seminar
"Tuning of spin-orbital interactions and charge gap by epitaxial strain in Sr2IrO4"
Presented by Thorsten Schmitt, Photon Science Division, Paul Scherrer Institut, Switzerland
Monday, February 24, 2020, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Mark Dean
The nature of the highly spin-orbit coupled Mott state of Sr2IrO4 suggests the ground state as well as the collective entangled spin and orbital excitations to be strongly dependent on the lattice degree of freedom. For this reason, Sr2IrO4 provides an ideal platform for controlling the physical properties of a correlated material by inducing local lattice distortions. We use epitaxial strain to modify the Ir-O bond geometry and perform momentum-dependent Resonant Inelastic X-ray Scattering (RIXS) both at the metal and ligand sites to unveil the response of the low energy elementary excitations. By applying tensile strain, we observe a large softening of the spin(-orbital) wave dispersion along the [h,0] direction and a simultaneous hardening along the [h,h] direction. This evolution entails a strain-driven crossover from anisotropic to isotropic interactions between the magnetic moments. We also show how the charge excitations are coupled to the lattice in Sr2IrO4. To this end, using O K-edge RIXS, we unveil the evolution of a dispersive electron-hole pair excitonic mode which shifts to lower (higher) energies upon compressive (tensile) strain, manifesting a reduction (increase) in the size of the charge gap. We show that this behavior originates in the modified hopping elements between the t2g orbitals induced by strain. Our work highlights the central role played by the lattice in determining both the spin(-orbital) as well as the charge excitations of Sr2IrO4 and confirms epitaxial strain as a promising route towards the control of the ground state of complex oxides in the presence of high spin-orbit coupling.
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Condensed-Matter Physics & Materials Science Seminar
"Field-theoretical approach to strongly-correlated problems: RIXS in metals and Spin fermion model"
Presented by Igor Tupitsyn, University of Massachusetts Amherst
Monday, February 24, 2020, 11 am
ISB Bldg. 734 Conf. Rm. 201 (upstairs)Hosted by: Alexei Tsvelik
In this talk I am going to touch two interesting strongly-correlated problems: Resonant inelastic x-ray scattering (RIXS) in metals and Spin fermion (SF) model. RIXS is a very promising technique for studying collective excitations in condensed matter systems. However, extraction of information from the RIXS signal is a difficult task and the standard approach to solution of RIXS problem is based on approximations that are inaccurate in metals (short-range/contact potentials and non-interacting Fermi-sea). Simultaneously, the SF model has a wide range of applications in the physics of cuprates and iron-based superconductors. However, all developments and applications of the SF model are also based on various, often uncontrollable, approximations. In my talk I am going to address both problems within the general "field-theoretical approach to strongly-correlated problems" framework. In the first part I will consider the RIXS in metals problem within a diagrammatic approach that fully respects the long-range Coulomb nature of interactions between all charged particles. In particular, I will demonstrate how the single-plasmon dispersion can be extracted from the multi-excitation RIXS spectra. In the remaining time I will briefly discuss how to deal with the SF model in the approximation-free manner by employing the Diagrammatic Monte Carlo technique, combining the advantages of Feynman diagrammatic techniques and Quantum Monte Carlo simulations. I will also show what one can get in the first skeleton order – in the widely used in materials science GW approximation.
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NT/RIKEN Seminar
"Soft Fragmentation on the Celestial Sphere"
Presented by Duff Neill
Friday, February 21, 2020, 2 pm
Building 510, CFNS Room 2-38Hosted 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.
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NSLS-II Friday Lunchtime Seminar
"Effect of Metal (Pt, Ir) Nuclearity in the Subnanometer Regime on CO Oxidation Activity"
Presented by Ayman M. Karim, Department of Chemical Engineering, Virginia Polytechnic Institute and State University
Friday, February 21, 2020, 12 pm
NSLS-II Bldg. 743 Room 156Hosted by: Ignace Jarrige
Supported noble metal catalysts are extensively used in industry and their catalytic performance is strongly affected by particle size and shape. In the last decade, supported single atoms and clusters in the subnanometer size regime have attracted a lot of interest since they maximize the metal utilization and have also shown extraordinary catalytic properties for many reactions. However, to tailor the catalyst properties for specific reactions and determine possible limitations, there is a need to understand, on the atomic scale, the origin of reactivity in the subnanometer regime. In this seminar, I will present my group's efforts in understanding the role of metal nuclearity and electronic properties in catalyzing CO oxidation as a model reaction. Using a suite of advanced characterization techniques (aberration-corrected electron microscopy, microcalorimetry, in-situ and in-operando DRIFTS, XPS, EXAFS and HERFD-XANES) complemented by DFT calculations and detailed kinetics measurements, the catalyst structural and electronic properties are identified and correlated with the reaction kinetics. In the talk, CO oxidation on Ir and Pt single atoms and subnanometer clusters supported on MgAl2O4 and CeO2, respectively, will be presented. We identified the active Ir and Pt single atom complexes and show that the reaction follows a combination of Eley-Rideal and Mars-van Krevelen mechanisms. Moreover, we show that despite considered a non-reducible support, CO oxidation on MgAl2O4 supported Ir subnanometer clusters follows a similar mechanism as on a reducible oxide where O2 is activated at the metal-support interface. Finally, the role of metal-support interaction in O2 activation and effect of CO binding strength on the catalytic activity will be discussed.
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Particle Physics Seminar
"Precision neutrino oscillation physics and DUNE"
Presented by Callum Wilkinson, University of Bern
Thursday, February 20, 2020, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Hanyu Wei
Neutrino oscillations have been established as an energy and distance dependent phenomena, beyond the Standard Model of Particle Physics. However, a number of key questions remain, which have implications for our understanding of the origin and development of our Universe. The Deep Underground Neutrino Experiment (DUNE), which is currently in the planning stage, has the potential to answer these outstanding questions and make measurements of the other parameters with unprecedented precision. This talk gives an overview of the DUNE sensitivity to oscillation parameters, and describes a program of research aimed at reducing systematic uncertainties, and achieving DUNE's physics goals.
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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 1-224Hosted 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.
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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 2-38Hosted 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.
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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 2-38Hosted 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.
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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 2-38Hosted 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.
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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 2-160Hosted 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.
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HET Seminar
"BBN and CMB bounds on hidden sector vectors"
Presented by Graham White, TRIUMF
Wednesday, February 12, 2020, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Rob Pisarski
New dark vector bosons that couple very feebly to regular matter can be produced in the early universe and decay after the onset of Big Bang Nucleosynthesis (BBN) or the formation of the cosmic microwave background (CMB) at recombination. The energy injected by such decays can modify the light element abundances or modify the power and frequency spectra of the CMB. In this work we study the constraints implied by these considerations on a range of sub-GeV dark vectors including the kinetically mixed dark photon, as well as gauge B-L and lepton families. We focus on the effects of electromagnetic energy injection, and we update previous investigations of the dark photon by taking into account non-universality in the photon cascade spectrum relevant for BBN and the energy dependence of the ionization eciency after recombination in our treatment of modications to the CMB.
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Physics Colloquium
"What ever happened to the WIMP of tomorrow?"
Presented by Philip 'Flip' Tanedo, UC Riverside
Tuesday, February 11, 2020, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Gopolang Mohlabeng
The overwhelming observational evidence for the existence of dark matter is only matched by the awkward scarcity of information about what it might actually be. Laboratory searches for dark matter now appear to exclude many of the "weakly interacting massive particle" models that were favored by particle physicists for decades. Where does that leave the hunt for dark matter? If we've left the WIMP behind, what are we looking for? We give a brief, biased, and largely fictional history of the WIMP in order to establish what has and has not been excluded, and why it matters. This general-interest presentation grew out of discussions with astronomers who wanted to understand why some of their particle physics colleagues are "searching for WIMPs" while the others have decided to live in a "post-WIMP world".
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Nuclear Physics Seminar
"Heavy flavor physics from ATLAS"
Presented by Qipeng Hu, University of Colorado at Boulder
Tuesday, February 11, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jiangyong Jia
In A+A collisions, heavy-flavor (charm and bottom) quarks are created at the initial stage of the collision and experience the entire QGP evolution. Therefore, they serve as penetrating probes that traverse the hot and dense medium, interact with the partonic constituents of the plasma and lose energy. Studies of production rate and azimuthal anisotropy of heavy-flavor hadrons provide insight into the energy loss mechanism and transport properties of heavy quarks in the QGP. To better understand the baseline of heavy quark—QGP interaction and the origin of the azimuthal anisotropy, it's crucial to extend the heavy-flavor measurements to smaller systems like p+Pb and pp collisions. In this seminar, selected results on the production and azimuthal anisotropy of the muons from charm and bottom hadron decays in pp, p+Pb and Pb+Pb collisions with the ATLAS experiments at the LHC will be shown. The implications for our understanding of the QGP properties by comparing the results with model calculations will be discussed.
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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 2-38Hosted 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.
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Condensed-Matter Physics & Materials Science Seminar
"Emergent phenomena from disorder on a 3D Topological Insulator surface"
Presented by Yishuai Xu, New York University
Friday, February 7, 2020, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Mark Dean
Three-dimensional topological insulators are bulk insulators with Z2 topological order that gives rise to Dirac surface states. These surface states are well protected against weak perturbations that do not break time-reversal symmetry, such as non-magnetic scalar potential disorder. However recent studies have shown that non-magnetic point defects can introduce new in-gap states. We developed a numerical model to simulate point defects on a TI surface, and performed linear-dichroic angle resolved photoemission (ARPES) to image these states in the surface electronic structure. We find that resonance states associated with the defects can hybridize with the Dirac cone surface state and create a kink-like feature in the band structure near the Dirac point. These resonance states are not Anderson localized even though they cluster around the defects sites, and at higher densities, the kink feature is predicted to evolve into a new distinct band that can support diffusive transport. We also present ARPES spectromicroscopy measurements that more clearly resolve the interplay of Dirac surface states with real-space structure.
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Condensed-Matter Physics & Materials Science Seminar
"RIXS study of charge dynamics in cuprates"
Presented by Jiaqi Lin, Chinese Academy of Sciences / BNL
Thursday, February 6, 2020, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Mark Dean
The charge dynamics in cuprates is not comprehensively studied due to the limitation of experimental methods. Resonant inelastic x-ray scattering (RIXS) is a technique that is capable of coupling to various types of excitations and recently has been established as a new way to probe charge density response. Here we use RIXS technique to study two types of charge excitations, the plasmon excitations in electron-doped cuprates and the charge density wave (CDW) excitations in hole-doped cuprates. 1) We track the doping dependence of charge excitations in electron-doped cuprates La2-xCexCuO4. From the resonant energy dependence and the out-of-plane momentum dependence, the charge excitations are identified as three-dimensional plasmons, which reflect the nature of the electronic structure and Coulomb repulsion on both short and long length scale. With increasing electron doping, the plasmon excitations increase monotonically in energy and life time, which reflects the reduction of short-range electronic correlation. 2) We report a comprehensive RIXS study of La2−xSrxCuO4 finding that CDW effects persist up to a remarkably high doping level of x = 0.21 before disappearing at x = 0.25. The inelastic excitation spectra remain essentially unchanged with doping despite crossing a topological transition in the Fermi surface. This indicates that the spectra contain little or no direct coupling to electronic excitations near the Fermi surface, rather they are dominated by the resonant cross-section for phonons and CDW-induced phonon-softening. We interpret our results in terms of a CDW that is generated by strong correlations and a phonon response that is driven by the CDW-induced modification of the lattice.
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Physics Colloquium
"New opportunities in neutrino physics"
Presented by Pedro Machado, Fermilab
Tuesday, February 4, 2020, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Peter Denton
In this colloquium I will briefly review the current status of neutrino physics and I will present new opportunities that will be unfolded by the future neutrino program. Some of these opportunities are incremental over past ones, while others are genuinely new. I will also emphasize the interplay between neutrino and other sectors in probing physics beyond the standard model.
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Nuclear Physics Seminar
"Global and local polarization of Lambda hyperons in Au+Au collisions"
Presented by Takafumi Niida
Tuesday, February 4, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Rongrong Ma
The matter created in non-central heavy-ion collisions is expected to have an initial angular momentum carried by two colliding nuclei. Such an initial angular momentum would be transferred to the global polarization due to the spin-orbit coupling. The STAR Collaboration observed \Lambda global polarization in Au+Au collisions at \sqrt{s_{NN}} = 7.7—200 GeV, indicating a thermal vorticity of the system. The detailed structure of the vorticity field may be complicated. Local vorticity and consequently the particle polarization may arise from jets and/or collective flow. In this talk, recent results on the polarization along the beam direction expected from the elliptic flow will be presented and the physics implications will be discussed with theoretical calculations.
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HET Seminar
"Phase transitions in the early Universe"
Presented by Djuna Croon, TRIUMF
Thursday, January 30, 2020, 2:30 pm
Small Seminar Room, Bldg. 510In anticipation of the next generation of gravitational wave experiments, I will discuss the opportunities for phenomenological studies of particle physics in the Early Universe. The focus of the talk will be on first order phase transitions in confining gauge theories. Such phase transitions may play an important role in explanations of the strong CP-problem, as well as in models of baryogenesis. I will discuss several such examples and their phenomenology.
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Condensed-Matter Physics & Materials Science Seminar
"Effect of Zeeman coupling on the Majorana vortex modes in iron-based topological superconductors"
Presented by Pouyan Ghaemi, The City College of New York
Tuesday, January 28, 2020, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Peter D. Johnson
In the superconducting regime of FeTe(1−x)Sex, there exist two types of vortices which are distinct by the presence or absence of zero energy states in their core. To understand their origin,we examine the interplay of Zeeman coupling and superconducting pairings in three-dimensional metals with band inversion. Weak Zeeman fields are found to suppress the intra-orbital spin-singlet pairing, known to localize the states at the ends of the vortices on the surface. On the other hand, an orbital-triplet pairing is shown to be stable against Zeeman interactions, but leads to delocalized zero-energy Majorana modes which extend through the vortex. In contrast, the finite-energy vortex modes remain localized at the vortex ends even when the pairing is of orbital-triplet form. Phenomenologically, this manifests as an observed disappearance of zero-bias peaks within the cores of vortices upon increase of the applied magnetic field. The presence of magnetic impurities in FeTe(1−x)Sex, which are attracted to the vortices, would lead to such Zeeman-induced delocalization of Majorana modes in a fraction of vortices that capture a large enough number of magnetic impurities. Our results provide a possible explanation to the dichotomy between topological and non-topological vortices recently observed in FeTe(1−x)Sex.
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HET Seminar
"New physics in rare decays"
Presented by Julian Heeck, UC Irvine
Monday, January 27, 2020, 2:30 pm
Small Seminar Room, Bldg. 510Despite its many successes, the Standard Model of particle physics cannot be the final description of nature at the most fundamental level. Additional elementary particles and interactions are an absolute necessity but have so far evaded our experimental efforts. I will highlight the importance of searches for processes that are forbidden within the Standard Model, as these make for clean signatures of new physics. Important examples are searches for lepton flavor violation and baryon number violation, which will be tested to unprecedented levels in upcoming experiments.
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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 2-38Hosted 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.
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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 2-160Hosted 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.
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Nuclear Physics Seminar
"Charmonia in Small Systems"
Presented by Krista Smith, Florida State University
Tuesday, January 21, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jin Huang
in heavy systems, but has also become an interesting probe in small sys- tems, having been studied by ALICE, ATLAS, CMS, LHCb, PHENIX and STAR. With the recent Nature paper PHENIX published regarding v2 and v3 coe_cients consistent with hydrodynamic ow and the possibil- ity of droplets of QGP present in small system collisions, measurements on the modi_cation of Charmonium in these same small systems have become increasingly relevant. We present the results of J/ measure- ments in the dimuon decay channel for a collection of di_erent systems at the same collision energy. These small systems include: p+p, p+Al, p+Au and 3He+Au at collision energy p SNN = 200 GeV. A comparison of Charmonium modi_cation in 3He+Au and p+Au data was made to look for e_ects of the increased energy present in the _nal state for the 3He+Au case. The results are presented in the form of the observable RAB, the nuclear modi_cation factor, as a function of rapidity, central- ity and transverse momentum, then compared with di_erent theoretical model predictions. Also included in this discussion are future plans to ex- tract the nuclear modi_cation factor for the (2s), the _rst excited state of the J/ meson.
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Condensed-Matter Physics & Materials Science Seminar
"Interlayer charge dynamics in metallic transition metal dichalcogenides"
Presented by Edoardo Martino, Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland
Tuesday, January 21, 2020, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Christopher Homes
Layered metallic transition metal dichalcogenides (TMDs) are conventionally seen as two-dimensional conductors, despite a scarcity of systematic studies of the interlayer charge transport. Motivated by the prevailing strategy of functionalizing 2D materials by creating van der Waals heterostructures, we initiated an in-depth study of out-of-plane charge dynamics and emergent properties arising from interlayer coupling. Unprecedented results have been obtained thanks to employing Focused-ion-beam-assisted 3D microfabrication of samples, which enables tailoring geometry and current paths with submicron precision [1]. In this talk, I will present the first transport data revealing c-axis-oriented quasi-one- dimensional electronic states in 1T-TaS2, —a compound with the richest charge density wave phase diagram among TMDs. Temperature dependence of resistivity shows a robust coherent out-of-plane transport, while in-plane conduction is hindered by the presence of a unique nanoarray of charge density wave domains. Consequently, we interpret the highly debated metal-insulator transition in 1T-TaS2 as a Peierls-like instability of the c-axis-oriented orbital chains, in opposition to the long-standing Mott localization picture [2]. Among other highlights of our current research are the anomalous transport properties observed in natural heterostructures or arising from stacking faults. [1] Moll, P. J. (2018). Focused ion beam microstructuring of quantum matter. Annual Review of Condensed Matter Physics, 9, 147-162. [2] Martino, E., Pisoni, A., Ciric, L., Arakcheeva, A., Berger, H., Akrap, A., ... & Forró, L. (2019). Preferential out-of-plane conduction and quasi-one-dimensional electronic states in layered van der Waals material 1T-TaS2. arXiv preprint arXiv:1910.03817.
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HET Seminar
"A Model of neutrino masses and the LHC"
Presented by Seyda Ipek, UC Irvine
Thursday, January 16, 2020, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Peter Denton
Neutrino masses cannot be explained within the Standard Model. Many new physics models address this question by adding right-handed neutrinos to the SM. These right-handed neutrinos are not expected to be observed at the LHC due either to their large masses or small couplings to the SM particles. I will give a different approach, in which we account for the SM neutrino masses via a pesudo-Dirac bino in an R-symmetric SUSY model. I will also give a recast of recent LHC analyses, mainly jets+MET and leptoquark searches, for this model.
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Condensed-Matter Physics & Materials Science Seminar
"Symmetry Protected Topological Semimetals"
Presented by Jennifer Cano, SUNY-Stony Brook
Thursday, January 16, 2020, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)Hosted by: Mark Dean
Topological semimetals can exhibit gapless Fermi arc surface states and unusual transport properties. I will discuss new aspects of the bulk-edge correspondence that elucidate the topological nature of Dirac fermions. I will then present the classification of nodal fermions in both magnetic and non-magnetic space groups. Finally, I will present an outlook for finding material realizations.
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HET Seminar
"Resolving CP Confusion from Non-Standard Neutrino Interactions"
Presented by Jeff Hyde, Bowdoin
Wednesday, January 15, 2020, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Peter Denton
Non-standard neutrino interactions (NSI) can interfere with measurements of neutrino oscillation parameters at long-baseline experiments, in particular making determination of the CP-violating phase δ ambiguous. Measurements at different baselines or energies may be combined to improve this situation, but it can be difficult to see the influence of individual parameters and determine when degeneracies may exist or be broken. I will show how the relationship between underlying parameters, degeneracies and their breaking may be represented in a convenient way in biprobability space. An application of particular interest is the experimental hints suggesting δ∼−π/2 , which could be consistent with nonzero NSI but the absence of CP violation.
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CSI Q Seminar
"Postponing the orthogonality catastrophe: efficient state preparation for electronic structure simulations on quantum devices"
Presented by Norman Tubman, NASA Quantum Artificial Intelligence Laboratory
Wednesday, January 15, 2020, 1:30 pm
Training Room, Bldg 725Hosted by: Layla Hormozi
Despite significant work on resource estimation for quantum simulation of electronic systems, the challenge of preparing states with sufficient ground state support has so far been largely neglected. We investigate this issue in several systems of interest, including organic molecules, transition metal complexes, the uniform electron gas and Hubbard models. Our approach uses a state-of-the-art classical technique for high-fidelity ground state approximation. We find that easy-to-prepare single Slater determinants such as the Hartree-Fock state often have surprisingly robust support on the ground state for many applications of interest. For the most difficult systems, single-determinant reference states may be insufficient, but low-complexity reference states may suffice. For this we introduce a method for preparation of multi-determinant states on quantum computers.
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Physics Colloquium
"The interface between Arts and Science, a multi-dimensional space"
Presented by Helio Takai, Interim Dean, School of Liberal Arts and Sciences, The Pratt Institute
Tuesday, January 14, 2020, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: George Redlinger
The interface between Arts and Science is wide and diverse. Art and Design covers a wide range of activities from Fine Arts to Digital Arts, from Fashion to Industrial Design, and Architecture. In this context, the disciplines of mathematics and sciences have a broad overlap with these creative practices. The science, and technology, from the knowledge of materials to software for virtual and augmented reality, are all foundations to the development of Arts and Design. In all of these areas, one of the main concerns today is the evolution of these practices in a sustainable and ecological manner. Biomaterials, Material Degradation, Software Development, and Robotics, are a few of the subjects relevant to Arts and Design. On the counter flux, Arts can bring new ways to communicate science to a large segment of the population. Art communicates a message through experiences. In this presentation, I will discuss the various interfaces between arts and science, and in particular, those that are relevant to the Pratt Institute.
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Nuclear Physics Seminar
"Study of nuclear effects in small collision systems connecting proton-proton and heavy-ion collisions"
Presented by Sanghoon Lim, Pusan National University
Tuesday, January 14, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jin Huang
The main purpose of relativistic heavy-ion collision experiments is to understand QuarkGluon Plasma (QGP) which is very hot and dense QCD matters produced in heavy-ion collisions. Early results from RHIC such as jet quenching and elliptic flow are supported for the formation of the QGP. In order to fully understand the properties of the QGP, it is very important to understand initial conditions before the QGP formation. Proton(deuteron)-ion collision is a control experiment to explore this kind of effects from intrinsic nucleus so called cold-nuclear-matter (CNM) effects such as modification of parton · distributions, energy loss, multiple scattering, and break-up of quarkonia states. Another striking results recently observed in small systems are long-range correlations which were believed as one of properties of the QGP. Now, the studies in small systems receives much more attention than that as a control experiment of heavy-ion collisions. I will introduce the interesting results in small collision systems as well as what we can learn from the expected measurements in the future.
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CSI Q Seminar
"Quantum-Assisted Telescope Arrays"
Presented by Emil Khabiboulline, Harvard University
Monday, January 13, 2020, 3 pm
Training Room, CSI Bldg 725Hosted by: Andrei Nomerotski
Quantum networks provide a platform for astronomical interferometers capable of imaging faint stellar objects. We present a protocol with efficient use of quantum resources and modest quantum memories. In our approach, the quantum state of incoming photons along with an arrival time index is stored in a binary qubit code at each receiver. Nonlocal retrieval of the quantum state via entanglement-assisted parity checks at the expected photon arrival rate allows for direct extraction of phase difference, effectively circumventing transmission losses between nodes. Compared to prior proposals, our scheme (based on efficient quantum data compression) offers an exponential decrease in required entanglement bandwidth. We show that it can be operated as a broadband interferometer and generalized to multiple sites in the array. We also analyze how imaging based on the quantum Fourier transform provides improved signal-to-noise ratio compared to classical processing. Finally, we discuss physical realizations including photon detection-based quantum state transfer. Experimental implementation is then feasible with near-term technology, enabling optical imaging of astronomical objects akin to well-established radio interferometers and pushing resolution beyond what is practically achievable classically. References: Phys. Rev. Lett. 123, 070504, Phys. Rev. A 100, 022316
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HET Seminar
"Experimental Probe of Higgs Parity"
Presented by Keisuke Harigaya, IAS
Monday, January 13, 2020, 2:30 pm
Small Seminar Room, Bldg. 510Hosted by: Peter Denton
Higgs Parity is a spontaneously broken Z2 symmetry exchanging the standard model Higgs with its parity partner. Higgs Parity predicts a dark matter candidate, can solve the strong CP problem, and can be a part of an SO(10) grand unified gauge symmetry. I will show that the Higgs Parity symmetry breaking scale is determined by standard model parameters and predicts experimental signals such as the dark matter detection rate and the proton decay rate. As a result, Higgs Parity provides a tight correlation between future precision measurements of standard model parameters and these experimental signals.
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Physics Colloquium
"The Proton Remains Puzzling"
Presented by Haiyan Gao, Duke University
Tuesday, January 7, 2020, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: Xin Qian
Nucleons (protons and neutrons) are the building blocks of atomic nuclei, and are responsible for more than 99% of the visible matter in the universe. Despite decades of efforts in studying its internal structure, there are still a number of puzzles surrounding the proton such as its spin, mass, and charge radius. The proton charge radius puzzle developed about ten years ago refers to a 5-7 sigma discrepancy between the ultrahigh precise values of the proton charge radius determined from muonic hydrogen Lamb shift measurements and the CODATA values compiled from electron-proton scattering experiments and hydrogen spectroscopy measurements. In this talk I will briefly introduce the proton spin and mass puzzles first. I will then focus on the proton charge radius puzzle, the latest experimental results, and especially the PRad experiment at Jefferson Lab and its result.
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Chemistry Department Colloquium
"Design of high voltage all-solid-state batteries based on sulfide electrolytes"
Presented by Xin Li, John A. Paulson School of Engineering and Applied Sciences, Harvard University
Tuesday, January 7, 2020, 2 pm
Hamilton Seminar Room, Bldg. 555Hosted by: Enyuan Hu
Ceramic sulfide solid-electrolytes are amongst the most promising materials for enabling solid-state lithium ion batteries. The ionic conductivities can meet or exceed liquid-electrolytes for such ceramic sulfides, however, there is a theoretical concern about the narrow electrochemical stability window of approximately 1.7-2.1 V vs lithium metal. In addition, ceramic sulfides are frequently plagued by interfacial reactions when combined with common electrode active materials. In this talk, methods for the stabilization of both the bulk electrochemical decompositions and the interfacial reactions will be discussed. Ceramic sulfides are known to substantially swell during electrochemical decay. Such swelling has been shown to provide viable means by which to stabilize electrochemical decomposition in lithium ion batteries. Experimental evidence and theoretical understanding of stability window expansion as the result of mechanical constriction will be discussed. An advanced mechanical constriction technique is applied on all-solid-state batteries constructed with Li10GeP2S12 (LGPS) as the electrolyte and lithium metal as the anode. The decomposition pathway of LGPS at the anode interface is modified by this mechanical constriction and the growth of lithium dendrite is inhibited, leading to excellent rate and cycling performances. On the cathode side, 5V all-solid-state batteries using layered LiCoO2 and spinel as cathodes will be presented and the stabilization mechanisms will be discussed. A combination of electrochemical battery tests, SEM, XAS, XPS and XRD characterizations, and DFT simulations was used. Biosketch Xin Li is an associate professor of materials science at School of Engineering and Applied Sciences (SEAS) at Harvard University, who was an assistant professor at SEAS from 2015 to 2019. Xin Li's research group designs new energy storage materials through advanced characterizations and simulations, with the current focus on solid s
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Nuclear Physics Seminar
"Physics with heavy ions and exotic hadrons at LHCb"
Presented by Matt Durham, Los Alamos National Lab
Tuesday, January 7, 2020, 11 am
Small Seminar Room, Bldg. 510Hosted by: Jin Huang
The LHCb Experiment has a growing program dedicated to heavy ion physics. With full tracking, particle ID, and calorimetry capabilities over the forward rapidity interval 2 < y < 5, LHCb covers a unique kinematic range at the LHC. This allows LHCb to fully reconstruct heavy quark states that are sensitive to the very low x structure of nucleons, as well as characterize exotic states that may be composed of more than three valence quarks. This talk will discuss recent results from the LHCb heavy ion program, with a focus on using heavy ion data and techniques to probe the structure of exotic hadrons.
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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 2-38Hosted 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.
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CSI Q Seminar
"Probing quantum entanglement at the Electron Ion Collider"
Presented by Dmitri Kharzeev, Stony Brook University and BNL
Wednesday, December 18, 2019, 1:30 pm
Training Room, Bldg 725Hosted by: Layla Hormozi
The structure functions measured in deep-inelastic scattering are related to the entropy of entanglement between the region probed by the virtual photon and the rest of the hadron. This opens new possibilities for experimental and theoretical studies using the Electron Ion Collider. The real-time evolution of the final state in deep-inelastic scattering can be addressed with quantum simulations using the duality between high energy QCD and the Heisenberg spin chain.
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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 2-38Hosted 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.
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CSI Q Seminar
"Integrating ballistic graphene with superconducting resonators - A new building block for detectors and quantum circuits"
Presented by Olli Saira, BNL
Wednesday, December 11, 2019, 1:30 pm
Training Room, Bldg 725Hosted by: Layla Hormozi
I present measurements of a bolometer device based on boron nitride-encapsulated graphene operating at temperatures of 300 mK and below. Our experiment probes the exquisite properties of graphene that make it an appealing material for detector applications. First, the specific heat of electronic excitations in graphene is low, promising excellent sensitivity as a thermal photodetector. Second, at low temperatures, superconductivity can be induced in a localized region within the flake. This enables the integration of graphene with superconducting microwave circuits routinely used in quantum processors and astronomical detector arrays. Our initial results demonstrate the operating principle of a graphene bolometer with resonator-coupled temperature readout. However, we also observed unexpected heat leakage out of the flake in our first-generation device, which prevented it from reaching its full theoretical performance.
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Condensed-Matter Physics & Materials Science Seminar
"In-situ TEM sample-management solutions Wildfire and Lightning Heating and Biasing – capturing real dynamics in TEM"
Presented by Yevheniy Pivak, DENSsolutions
Monday, December 9, 2019, 11 am
Bldg. 480, Conference RoomHosted by: Shaobo Cheng
DENSsolutions offers a complete suite of in-situ sample management solutions for unrivalled high resolution imaging in Transmission Electron Microscopes (TEM) under varying environmental conditions including Heating, Biasing, Gases & Liquids. This presentation is aimed at researchers that want to observe their materials in varying real-time dynamic In-situ TEM environments at high resolution. The format of the presentation will include an explanation to the theory behind DENSsolutions' MEMS-based technology, along with brief products introduction. The main topic of the presentation is the Heating and/or Biasing system and its application in the fields of materials science, chemistry and microelectronics. Application examples such as solar cells, ceramics, ReRam, batteries, 2D materials and more will be covered.
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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 2-38Hosted 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.
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Particle Physics Seminar
"A New Paradigm for Dark Matter Search at the LHC"
Presented by Yangyang Cheng, Cornell University
Thursday, December 5, 2019, 3 pm
Small Seminar Room, Bldg. 510Hosted by: Ketevi Assamagan
The existence of dark matter (DM), through astrophysical and cosmological observations, presents some of the most striking evidence of physics beyond the Standard Model. Stringent limits have been placed on DM as a Weakly Interacting Massive Particle (WIMP) from direct and indirection detection as well as collider experiments. If instead of one type of DM particle, nature contains a complex dark sector, the new hidden particles can evade existing DM limits and most direct detection experiments, but may be produced at high-energy colliders like the LHC. Many dark sector models predict long-lived particles with striking collider signature, opening an exciting new paradigm for dark matter search. This talk overviews the landscape for dark matter search, and introduces the physics motivation for a complex dark sector with long-lived particles. It then describes two types of signature-driven dark sector searches at the CMS experiment, for a dark shower and for displaced lepton jets. Finally, the talk discusses prospects for dark sector searches at the High-Luminosity LHC with detector and trigger upgrades, in particular how the new forward detectors and enhanced timing capabilities can reach new phase spaces and sensitivities.
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CSI Q Seminar
"Quantum supremacy using a programmable superconducting processor"
Presented by Pedram Roushan, Google
Wednesday, December 4, 2019, 1:30 pm
Large Seminar Room, Bldg. 510Hosted by: Layla Hormozi
The promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor1. A fundamental challenge is to build a high-fidelity processor capable of running quantum algorithms in an exponentially large computational space. Here we report the use of a processor with programmable superconducting qubits to create quantum states on 53 qubits, corresponding to a computational state-space of dimension 2^53. Measurements from repeated experiments sample the resulting probability distribution, which we verify using classical simulations. Our Sycamore processor takes about 200 seconds to sample one instance of a quantum circuit a million times—our benchmarks currently indicate that the equivalent task for a state-of-the-art classical supercomputer would take approximately 10,000 years. This dramatic increase in speed compared to all known classical algorithms is an experimental realization of quantum supremacy for this specific computational task, heralding a much-anticipated computing paradigm.
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Special HET Seminar (Joint BNL/YITP)
"Composite Higgs Models at the LHC and beyond"
Presented by Da Liu, UCDavis
Wednesday, December 4, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Peter Denton
Compositeness is an elegant way to address the hierarchy problem. In this talk, I will discuss about the phenomenology of the composite Higgs models at the LHC and beyond, in which Higgs arise as Nambu-Goldstone bosons. Under broad assumption of partial compositeness and symmetry breaking pattern, I will discuss about phenomenology of the spin-1 resonances and the top partners and the relevance of their strong interactions in the searches at the LHC. In addition to the direct searches, the LHC has become a precision machine with accumulating enormous data at the High-Luminosity (HL) stage. I will discuss about precision measurement in the di-boson processes and their relevance in the different new physics patterns. Meanwhile, I will talk about the strong multi-pole interaction scenario, in which the transverse SM gauge bosons are also belonging to the strong sector at the multi-TeV scale. This provided a strong motivation for the precision measurement at the LHC. Finally, I will briefly discuss about the universal relationship between the Higgs couplings predicted by the non-linearity and their phenomenological relevance.
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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 2-38Hosted 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.
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Physics Colloquium
"The First Stage of the International Linear Collider"
Presented by James Brau, University of Oregon
Tuesday, December 3, 2019, 3:30 pm
Large Seminar Room, Bldg. 510Hosted by: George Redlinger
The International Linear Collider is now proposed to begin with a first stage at 250 GeV with an initial integrated luminosity goal of 2 ab−1. I will review the plan for the collider and detectors, the key physics expectations, and recent international discussions. The key physics goal of the ILC250 is precision measurements of the Higgs boson couplings. The exceptional precision of model-independent measurements of all major decay modes makes this program sensitive to possible anomalies due to new physics beyond the Standard Model. Other physics goals will be addressed briefly. The ILC250 infrastructure will support an upgrade future of experiments with e+e− collisions at higher energy up to 1 TeV, building on the success of the first 250 GeV stage.
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Nuclear Physics Seminar
"Initial state fluctuations of QCD conserved charges in heavy-ion collisions"
Presented by Matt Sievert
Tuesday, December 3, 2019, 11 am
Small Seminar Room, Bldg. 510Hosted by: Alba Soto Ontoso
We initialize the Quantum Chromodynamic conserved charges of baryon number, strangeness, and electric charge arising from gluon splitting into quark-antiquark pairs for the initial conditions of relativistic heavy-ion collisions. A new Monte Carlo procedure that can sample from a generic energy density profile is presented, called Initial Conserved Charges in Nuclear Geometry (ICCING), based on quark and gluon multiplicities derived within the color glass condensate (CGC) effective theory. We find that while baryon number and electric charge have nearly identical geometries to the energy density profile, the initial strangeness distribution is considerable more eccentric and is produced primarily at the hot spots corresponding to temperatures of T > 400 MeV for PbPb collisions at 5.02 TeV.
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Special Physics Colloquium
"FCC-ee at CERN: High Precision and High Luminosity at the Electroweak Scale"
Presented by Alain Blondel, Guest Professor at CERN
Monday, December 2, 2019, 11 am
Large Seminar Room, Bldg. 510Hosted by: Maria Chamizo-Llatas / George Redlinger
Abstract: The discovery of the Higgs boson completed the Standard model and particle physics enters a new era, in which new phenomena are required, but at unknown energy scale and coupling strength. This requires a broad program of searches. The broadest program is offered by the Future Circular Collider (FCC) project at CERN, with a ultimate goal of reaching > 100 TeV in pp collisions. The first step of this program is a circular e+e- collider, offering unprecedented levels or precision and sensitivity to feebly coupled particles. Bio: Alain Blondel is Professor emeritus from University of Geneva and guest professor at CERN. He is leading the effort of physics and experiments for the Future Circular Collider FCC-ee at CERN, a high luminosity e+ e- machine able to produce 5x1012 Z, 108 WW events, 2x106 ZH events and more than 106 top quark pairs. The proposals for the FCC were just submitted to the CERN European Strategy for Particle Physics, which hopefully will endorse the FCC 100km facility around CERN providing powerful means to search for answers to the big questions. He previously worked in the T2K experiment, preparing HyperK, towards neutrino CP violation. He has a long career since 1974, with the Gargamelle experiment and LEP as highlights, and was awarded a number of prizes for his creative work, in particular on the determination of the number of neutrinos and the prediction of the top quark mass from radiative corrections.
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