Bulletin of the American Physical Society
2019 Fall Meeting of the APS Division of Nuclear Physics
Volume 64, Number 12
Monday–Thursday, October 14–17, 2019; Crystal City, Virginia
Session GJ: Mini-symposium: Quantitative Understanding of QGP Properties III |
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Chair: Nathan Grau, Augustana University Room: Salon C |
Tuesday, October 15, 2019 2:00PM - 2:36PM |
GJ.00001: Towards a quantitative understanding of the QGP: experimental perspectives Invited Speaker: Ron Belmont Heavy ion physics is rapidly becoming a quantitative field. While the field is rich and varied with many important subfields, all these can be divided into roughly two main categories: hard probes and bulk quantities. Both are essential to understanding the inner workings of the QGP and developing a full quantitative picture. In this talk we will address both categories, what measurements are needed, and what future facilities will help accomplish these goals. [Preview Abstract] |
Tuesday, October 15, 2019 2:36PM - 2:48PM |
GJ.00002: Nuclear modification factor of neutral pions in p+A, d+Au and 3He+Au collisions in PHENIX Niveditha Ram The suppression of neutral pion production in Au+Au collisions at RHIC, and lack of suppression in d+Au collisions are evidence a QGP was formed (in Au-Au collisions) in which hard scattered partons-in a final state effect-lose energy. Initial state, or "cold nuclear matter" effects, including the Cronin-effect, were expected to dominate very asymmetric (small on large) collisions. Recently, however, collectivity has been observed in p/d/He+A collisions, consistent with the formation of QGP droplets. While this does not necessarily imply hadron suppression, as in central Au+Au collisions, earlier d+Au results suggested exactly that, along with a surprising enhancement in peripheral d+Au. In this talk we will present the results of a systematic study of the neutral pion nuclear modification factor in p+Al, p+Au, 3He+Au along with a re-analysis of the d+Au data and compare them to previously published data and theoretical calculations. [Preview Abstract] |
Tuesday, October 15, 2019 2:48PM - 3:00PM |
GJ.00003: Charm quark directed, elliptic flows and diffusion coefficient from a multiphase transport model Xinyue Ju Open charm meson directed flow ($v_{1}$) and elliptic flow ($v_{2}$) is studied in relativistic heavy-ion collisions based on a multiphase transport model (AMPT) framework with partonic interactions. The key physics questions we would like to address are how charm quark $v_{1}$ and $v_{2}$ are developed in the parton cascade and how they are sensitive to the initial condition and charm quark spacial diffusion coefficient. We study the time evolution of charm quark $v_{1}$ and $v_{2}$ in the partonic phase and compare them with those of light flavor quarks. We find that the charm quark with initial $p_{x}$>0 ($p_{x}$<0) can preserve the large positive (negative) $v_{1}$ through the partonic cascade, suggesting charm quarks can retain the momentum kick caused by initial electro-magnetic field. Charm quark spatial diffusion coefficient is calculated and its dependence on partonic scattering cross section as well as its time evolution are studied to help understand how they get manifested in the $v_{1}$ and $v_{2}$ observables. These findings are expected to guide us on how to better constrain the initial tilt of the fireball and the temperature dependence of charm quark diffusion coefficient in ultra-relativistic heavy-iron collisions. [Preview Abstract] |
Tuesday, October 15, 2019 3:00PM - 3:12PM |
GJ.00004: Cold Nuclear Matter Effects on J/$\psi$ and $\Upsilon$ Productions at RHIC with the STAR Experiment Ziyue Zhang Quarkonia are excellent probes for studying the properties of quark-gluon plasma formed in relativistic heavy-ion collisions at RHIC. In order to fully understand the observed suppression of quarkonium production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV, it is essential to understand well the cold nuclear matter (CNM) effects on the quarkonium production. Collisions of p+Au at the same energy can be used to study the CNM effects since these effects are expected to be dominant in such systems. In this talk, we present measurements of inclusive J/$\psi$ and $\Upsilon$ cross-sections in p+p collisions and their modification in p+Au collisions (the nuclear modification factor $R_{pAu}$) at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV. The results are extracted from data recorded by the STAR experiment in 2015 using the di-electron decay channel of the quarkonia. Comparisons are made to results from other experiments as well as to model calculations and physics implications are also discussed. [Preview Abstract] |
Tuesday, October 15, 2019 3:12PM - 3:24PM |
GJ.00005: Measurement of the suppression and azimuthal anisotropy of heavy flavor muons in lead-lead collisions at 2.76TeV and proton-lead collisions at 5.02 TeV with the ATLAS detector Luke Krauth ATLAS measurements are presented on the production of muons from heavy-flavor decays in pp and Pb+Pb collisions at 2.76 TeV and in p+Pb collisions at 5.02 TeV. The measurements are performed over the transverse momentum range 4$ |
Tuesday, October 15, 2019 3:24PM - 3:36PM |
GJ.00006: Non-UPC production of dimuons from two-photon scattering in Pb+Pb collisions with the ATLAS detector Benjamin Gilbert In relativistic heavy-ion collisions the intense electromagnetic fields of the nuclei provide a large flux of equivalent photons. This flux leads to photon-photon and photon-nucleus reactions at high center-of-mass energies. In ultra-peripheral collisions, the nuclei have large impact parameter, and the dominant interaction mechanism is through these photon-induced processes. These photon-induced processes may also occur in events with smaller impact parameter, resulting in dimuons produced in the same events in which a hot nuclear medium is formed. This talk presents ATLAS measurements of $\gamma+\gamma\rightarrow\mu\mu$ in non-UPC collisions. The dimuons exhibit a centrality-dependent broadening of their azimuthal angle correlations suggesting that such muons provide a new probe of the medium. [Preview Abstract] |
Tuesday, October 15, 2019 3:36PM - 3:48PM |
GJ.00007: Study of the semileptonic decay of $D-$ and $B-$mesons into muons at $\sqrt{s_{NN}} = 200$ GeV with the PHENIX detector Ajeeta Khatiwada, Cesar Da Silva, Xuan Li We study yields of muons from the semileptonic decay of $D-$ and $B-$mesons at $\sqrt{s_{NN}}=200$ GeV with the data collected by the PHENIX experiment at RHIC. $D-$ and $B-$mesons are expected to leave signatures of displaced vertices in the tracking detectors that can be used to measure the relative contribution from charm and bottom hadrons to the muons in the Au+Au collision. Using p+p as control, this measurement will be carried out in the forward rapidity region, exploiting the excellent precision of event vertex and decay muons trajectories provided by the forward silicon-vertex detector and the central silicon-vertex detector. The measured cross section will probe $c-$ and $b-$quark yields in the quark-gluon plasma (QGP), give handle on the heavy quark energy loss in the QGP medium, and advance our understanding of the roles played by initial-state effects. In this talk, current status of the analysis and the techniques applied will be presented. [Preview Abstract] |
Tuesday, October 15, 2019 3:48PM - 4:00PM |
GJ.00008: Multiparticle correlations from the direct calculation of cumulants using particle azimuthal angles. Shengquan Tuo Instead of using the generating function or Q-cumulant methods for multiparticle correlation studies in heavy ion collisions, we calculate the cumulants directly looping over particle azimuthal angles. It is shown that this method is not possible for central and mid-central AA collisions due to the required computing resource, but possible for smaller collision systems and peripheral AA collisions. With this method we are able to study the correlations as a function of particle pseudorapidity gap between each particle in the multiparticle correlations. The method is tested with PYTHIA and HIJING models and it provides better statistical precision than the three subevent cumulant method with a pseudorapidity gap using the same amount of data. [Preview Abstract] |
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