Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session K15: Mini-Symposium: Results from RHIC Beam Energy Scan IILive Mini-Symposium
|
Hide Abstracts |
Sponsoring Units: GHP Chair: Matthew Sievert, New Mexico State University |
Sunday, April 18, 2021 1:30PM - 2:06PM Live |
K15.00001: THE RHIC Beam Energy Scan: What Have We Learned So Far and Where to Go Next Invited Speaker: Volker Koch I will try to give an overview of the key results and lessons learned from the RHIC Beam energy scan with a special focus on the search for the QCD critical point. I will further discuss what additional measurements, if any, may be needed to complete this search. [Preview Abstract] |
Sunday, April 18, 2021 2:06PM - 2:18PM Live |
K15.00002: Centrality Determination in the Fixed-Target Program at STAR Zachary Sweger The Glauber Model has long been used in heavy-ion collisions as a method of determining centrality by simulating nucleus-nucleus collisions and producing particles using a Negative Binomial Distribution (NBD). The core task is to determine what values of the negative binomial parameters and the hardness scaling reproduce the observed distributions from data, and assess whether adjustments to the particle production model are necessary to model multiplicities in the Fixed-Target Program (FXT). Particle production in heavy-ion collisions scales with the number of binary nucleon collisions for hard processes and with the number of participant or wounded nucleons for soft processes; the hardness scaling is an essential part of the Glauber Model and determines what fraction of produced particles are generated from soft versus hard processes. STAR has produced two fixed-target data sets at $\sqrt{s_{NN}}=3.0$ GeV and $7.2$ GeV which provide a unique opportunity to test the traditional particle production model. Attempts are made to fit simulated multiplicities to observed FXT multiplicity distributions using the hardness parameter and the negative binomial parameters. Several modifications to the particle production model will be explored. [Preview Abstract] |
Sunday, April 18, 2021 2:18PM - 2:30PM Live |
K15.00003: Cumulants: it's not what you think Agnieszka Sorensen, Volker Koch, Larry McLerran, Dmytro Oliinychenko Cumulants of baryon number are given considerable attention in analyses of heavy-ion collision experiments as possible signatures of the QCD critical point. In this talk, I will show that the values of the lowest three cumulants can also be utilized to recover information about the incompressibility, the speed of sound, and their logarithmic derivatives. I will then discuss the possible influence of the nuclear liquid-gas phase transition on the measured values of the cumulants. [Preview Abstract] |
Sunday, April 18, 2021 2:30PM - 2:42PM Live |
K15.00004: System Size Dependence of Net-charge and Net-proton Fluctuations From Au+Au and Ru+Ru/Zr+Zr-mixed Collisions at $\sqrt{s_{NN}}= 200 GeV$ From STAR Zhengxi Yan Fluctuations of conserved charges have been extensively studied as sensitive probes to the evolution of heavy-ion collisions. In 2018, the STAR experiment collected large datasets of isobaric collisions of Ru+Ru and Zr+Zr at 200 GeV, which provide an opportunity to study the conserved charge fluctuations with good precision and to compare with similar measurements from the larger Au+Au collision system. The identity of isobar collisions is currently blinded but we can still perform measurements using average of Ru+Ru and Zr+Zr (iso-mixed data). In this talk, we present measurement of cumulants of the net-proton and net-charge multiplicity distribution up to fourth-order from the Ru+Ru and Zr+Zr iso-mixed data. The results are compared with similar results from Au+Au collisions. [Preview Abstract] |
Sunday, April 18, 2021 2:42PM - 2:54PM Live |
K15.00005: Higher-order Cumulants of Proton Multiplicity Distributions in Au+Au Collisions at $\sqrt{s_{NN}}$ = 3 GeV from STAR Yu Zhang Experimental evidences at RHIC and the LHC have demonstrated the formation of Quark-Gluon Plasma (QGP) in ultra-relativistic heavy-ion collisions at small baryon chemical potential ($\mu_{B} \approx 0$ MeV) where the phase transition from the hadronic matter to QGP is suggested to be a crossover from state-of-the-art Lattice QCD calculations. It has been conjectured that there is a first-order phase transition and a critical point at finite $\mu_{B}$ region in the QCD phase diagram. In search of the possible QCD critical point, higher-order cumulants of conserved quantities (B, Q, S) are sensitive observables to locate its position. In this talk, we will report analysis status of higher-order cumulants of proton multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}$= 3 GeV collected by STAR at RHIC from the year 2018. Corresponding analysis techniques, like efficiency correction, pileup correction, and volume fluctuation correction will be discussed. [Preview Abstract] |
Sunday, April 18, 2021 2:54PM - 3:06PM Live |
K15.00006: Fluctuations in Lambda Multiplicity Distribution in Au+Au collisions at $\sqrt{s_{NN}}=3$ GeV at STAR Jonathan Gonzalo Ball Cap The study of nuclear matter over a wide energy range is provided by the RHIC Beam Energy Scan (BES). This program focuses on locating the critical end point (CEP) in the QCD phase diagram. One of the signatures used to locate the CEP is a non-monotonic behaviour as a function of $\sqrt{s_{NN}}$ of proxies such as the event-by-event net multiplicity fluctuations. Fluctuation in net-protons exhibited a non-monotonic behaviour in the region of $\sqrt{s_{NN}}=19.6$ GeV to $7.7$ GeV in the first phase of BES (BES-I), which motivated the increase in statistics and extending the collision energy down to $\sqrt{s_{NN}}=3.0$ GeV. The study of fluctuations in net-lambda multiplicity distribution allows to use its baryonic contribution for the search of the CEP. By using its non-diagonal baryon-strangeness correlator it allows along with proton-kaon correlations to study the difference in freeze-out temperatures for protons and strange particles. We present the event-by-event fluctuation analysis of the net lambda multiplicity distribution for the fixed target physics run at $\sqrt{s_{NN}}=3.0$ GeV which will be compared with the results of the previous net lambda fluctuation studies for BES-I and net-proton fluctuation. [Preview Abstract] |
Sunday, April 18, 2021 3:06PM - 3:18PM Live |
K15.00007: Vorticity and Polarization in Nucleus-Nucleus Collisions at sub-10-GeV Beam Energy Jinfeng Liao In a non-central nucleus-nucleus collision, the colliding system carries large orbital angular momentum, part of which remains within the hot dense matter created by the collision. This angular momentum turns into complex fluid vorticity structures in the bulk fluid, and eventually manifests itself through the global spin polarization of produced particles (e.g. hyperons). The STAR Collaboration reported the experimental discovery of this novel phenomenon in 2017. A crucial feature in establishing the intepretation is the predicted beam energy dependence, specifically a strong increase of fluid vorticity (and thus the polarization) when the collision beam energy is decresed from O(100) GeV to O(10) GeV range. In the latest Beam Energy Scan II experiment, these measurements have been pushed toward sub-10-GeV range through e.g. fixed target collisions. It is an important question of great interest as to whether the trend would continue into such low beam energy range. In this contribution, we report our latest theoretical analysis of the vorticity and polarization in the sub-10-GeV collisions and present predictions for relevant observables. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700