Bulletin of the American Physical Society
2013 Fall Meeting of the APS Division of Nuclear Physics
Volume 58, Number 13
Wednesday–Saturday, October 23–26, 2013; Newport News, Virginia
Session NH: Heavy Ion Collisions: Correlations, Fluctuations |
Hide Abstracts |
Chair: Paul Sorensen, Brookhaven National Laboratory Room: Pearl Ballroom III |
Saturday, October 26, 2013 8:30AM - 8:42AM |
NH.00001: QGP parameter extraction via a global analysis of event-by-event flow coefficient distributions Jonah Bernhard, Christopher Coleman-Smith, Peter Marcy, Steffen Bass A primary goal of heavy-ion physics is the measurement of the quark-gluon plasma specific shear viscosity $\eta/s$. Previous studies have placed bounds on $\eta/s$, typically by matching the centrality dependence of event-averaged $v_n$ coefficients between model and experiment. The ATLAS experiment has recently measured event-by-event $v_n$ distributions, which could provide a much more sensitive probe of $\eta/s$. Using a hybrid model with MC-Glauber and MC-KLN initial conditions, viscous 2+1D hydrodynamics, and the hadron cascade UrQMD, we calculate $v_n$ distributions over wide ranges of several model parameters including $\eta/s$. By calibrating the model to data, we extract the optimal values of each parameter and clarify the important features of a physically accurate model. [Preview Abstract] |
Saturday, October 26, 2013 8:42AM - 8:54AM |
NH.00002: System size dependence of collective flow in Cu+Cu and Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV Damian Reynolds The study of collective flow has been instrumental in estimating the transport coefficient $\eta/s$ of the quark gluon plasma (QGP), as well as for detailed insights into initial state fluctuations. Given the smaller system size produced in Cu+Cu collisions, viscous effects and fluctuations are expected to play a more important role in these collisions than in Au+Au collisions. Recent $v_{2,3}$ measurements obtained by the PHENIX experiment employ a two-particle azimuthal correlation method involving the azimuthal angle difference ($\Delta\phi$) between the charge-weighted hits in the Beam-Beam Counters (BBC) and tracks in the central arms of PHENIX. This technique ensures the large pseudorapidity gap necessary for minimizing non-flow effects. Results from these measurements will be presented and discussed. [Preview Abstract] |
Saturday, October 26, 2013 8:54AM - 9:06AM |
NH.00003: Measurement of reaction-plane correlations in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV within a multi-phase transport model Peng Huo, Jiangyong Jia In heavy ion collisions the initial geometry fluctuations can be studied using the measured harmonic flow coefficients $v_n$. Further information on these fluctuations can be obtained by measuring the correlations between the reaction plane angles $\Phi_n$ of different orders. Using a multi-phase transport (AMPT) model for Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV, we present a study of the correlations between $\Phi_n$ of different orders. Various correlators are built between two and three reaction planes. These correlations are estimated from correlations between event-plane angles $\Psi_n$ with a resolution correction accounts for the dispersion from $\Psi_n$ relative to $\Phi_n$. Results are compared with the ATLAS measurements and show good consistency for two plane correlations. These simulation results can help provide a good insight into the the experimental measurements. [Preview Abstract] |
Saturday, October 26, 2013 9:06AM - 9:18AM |
NH.00004: HENIX Measurements of Higher-order Flow Harmonics for Identified Charged Hadrons in Au+Au Collisions at $\sqrt {{s_{NN}}} $ = 39 - 200 GeV Yi Gu Collective flow measurements continue to play an important role in ongoing efforts to map out the temperature dependence of the transport coefficient $\frac{\eta}{s}(T)$, for the strongly interacting matter produced in heavy ion collisions at RHIC. Recently, the PHENIX experiment has performed a detailed set of measurements of the higher-order flow coefficients ($v_{n}$ for n=2,3,4), for both inclusive and identified charged hadrons at mid-rapidity. The results from these new measurements will be presented, as a function of $p_T$, centrality and beam collision energy, along with several scaling properties observed for these data. The role of these results as additional constraints for $\frac{\eta}{s}(T)$ will also be discussed. [Preview Abstract] |
Saturday, October 26, 2013 9:18AM - 9:30AM |
NH.00005: Is $v_3$ necessary or even informative in describing angular correlation data from RHIC and the LHC? Lanny Ray, Thomas Trainor, Duncan Prindle One of the more interesting observations from the heavy-ion program at RHIC and now at the LHC are long-range correlations on relative pseudorapidity at small azimuth opening angles. In 2010 Alver and Roland [1] suggested that this so-called same-side ridge could be explained in terms of higher-order, azimuth cosine distributions generated by event-wise energy density fluctuations in the initial-state plus hydrodynamic flow. Applications of third- and higher-order harmonics in analysis of angular correlations from heavy-ion collisions have become ubiquitous in the literature. However, we question the introduction of ``higher harmonics'' to the 2D data description. Extending previous work we examine the necessity and utility of $v_3$. We find that the net effect of $v_3$ is to accommodate minor non-Gaussian structure in the same-side 2D peak for $p_t$-integral correlations from RHIC. A single Gaussian hypothesis for those data is not falsified within statistics. Model ambiguities and instabilities resulting from $v_3$ are discussed and resolved. Lastly, we demonstrate that the 0-1\% angular correlation data for 2.76 TeV Pb-Pb collisions from ATLAS [2] do not require a $v_3$ component.\\[4pt] [1] Phys. Rev. C81, 054905 (2010).\\[0pt] [2] ATLAS, Phys. Rev. C86, 014907 (2012). [Preview Abstract] |
Saturday, October 26, 2013 9:30AM - 9:42AM |
NH.00006: Angular correlations between forward-rapidity muons and mid-rapidity charged particles in p-Pb collisions at $\surd $s$_{\mathrm{NN}}=$ 5.02 TeV Saehanseul Oh Two particle angular correlations have been used as a powerful tool in exploring particle production mechanism in relativistic heavy ion physics. Angular correlations between forward-rapidity muons (-4.0 \textless\ $\eta _{\mathrm{lab}}$ \textless\ -2.5) and mid-rapidity charged particles (-0.9 \textless\ $\eta_{\mathrm{lab}}$ \textless\ 0.9) are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV in 2013. These unique kinematics allow us to access the small-x region of the Pb nucleus, where high gluon densities are expected. Muon-hadron correlations, expected to have features that exhibit gluon saturation, are compared to calculations using a Color Glass Condensate (CGC) model, as well as mid-rapidity di-hadron correlations by the ALICE collaboration. Previous forward-rapidity two particle correlations in d-Au collisions at RHIC will also be compared. [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