Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session H15: Minisymposium on Hot, Dense Matter in Heavy Ion Collisions I |
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Sponsoring Units: DNP Chair: Victoria Greene, Vanderbilt University Room: Hyatt Regency Jacksonville Riverfront City Terrace 11 |
Sunday, April 15, 2007 8:30AM - 9:06AM |
H15.00001: Heavy Flavor for the Perfect Java (QGP) Invited Speaker: In this presentation, we will review the latest experimental data from relativistic heavy ion collisions on heavy quarks and heavy quarkonia. Heavy quarks produced early in the collision time evolution give us great insight about the properties of the medium as they propagate through and eventually hadronize. Implications of current and future measurements will be detailed. [Preview Abstract] |
Sunday, April 15, 2007 9:06AM - 9:18AM |
H15.00002: Heavy Flavor Hadrons in Statistical Hadronization of Strangeness-rich QGP Inga Kuznetsova, Johann Rafelski We study $b$, $c$ quark hadronization from QGP within the chemical nonequilibrium statistical hadronization model. The important final state nonequilibrium feature of this study is that we take into account the high strangeness and entropy content of QGP, conserving strangeness and entropy yields at hadronization. Presence of an excess of entropy, and strangeness, influences the final population of heavy flavor mesons and baryons in a fast transition between QGP and HG phases: in this case final heavy hadron yields are produced at the physical conditions of QGP breakup. We show how a given charm and/or bottom yield is distributed among different heavy flavor species (non-strange and strange heavy mesons, baryons, multi-heavy mesons and baryons). The high strangeness content favors strange heavy hadrons yields, resulting in a relative suppression of non-strange (multi)heavy hadrons yields, the suppressed $J/\Psi$ yield being of particular interest. [Preview Abstract] |
Sunday, April 15, 2007 9:18AM - 9:30AM |
H15.00003: J/$\psi ->$e$^{+}$e$^{-}$ measurements in Cu+Cu collisions at $\surd $s$_{NN }$= 200 GeV Kushal Das J/Psi production in Cu+Cu collisions at $\surd $s$_{NN}$= 200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) in the rapidity ranges $\vert $y$\vert \quad <$ 0.35 and 1.2 $< \quad \vert $y$\vert \quad <$ 2.2 and the transverse momentum range p$_{T} \quad <$ 10 GeV/c via the dielectron and dimuon decay channels. The J/Psi yield and the nuclear modification factor (R$_{AA})$ as a function of centrality, transverse momentum and rapidity were obtained and will be compared with results from p+p and Au+Au collisions at the same center-of-mass energy. The data shows a strong suppression in the J/Psi production as a function of centrality for the most central collisions that is independent of rapidity. A survey of theoretical models will be presented and compared with the J/Psi measurements. [Preview Abstract] |
Sunday, April 15, 2007 9:30AM - 9:42AM |
H15.00004: Strangeness Chemical Equilibration in QGP at RHIC and LHC Jean Letessier, Johann Rafelski We study, in the dynamically evolving QGP fireball formed in relativistic heavy ion collisions at RHIC and LHC, the growth of strangeness yield toward and beyond the chemical equilibrium. We account for the contribution of the direct strangeness production and evaluate the thermal-QCD strangeness production mechanisms. The specific yield of strangeness per entropy, $s/S$, is the primary target variable. We explore the effect of collision impact parameter, {\it i.e.}, fireball size, on kinetic strangeness chemical equilibration in QGP. Insights gained in study the RHIC data with regard to the dynamics of the fireball are applied to the study strangeness production at the LHC. We use these results and consider the strange hadron relative particle yields at RHIC and LHC in a systematic fashion. We consider both the dependence on $s/S$, and participant number dependence. [Preview Abstract] |
Sunday, April 15, 2007 9:42AM - 9:54AM |
H15.00005: Azimuthal correlations with identified strange trigger particles in $Cu+Cu$ collisions at $\sqrt{s_{NN}} = 200 GeV$ at RHIC Christine Nattrass Two particle correlations should yield information about particle production mechanisms in jets at RHIC energies. Using identified particles may reveal differences between baryons and mesons and between quark and gluon jets. Two particle azimuthal correlations in Cu+Cu collisions in the STAR detector at $\sqrt{s_{NN}} = 200 GeV$ with identified $\Lambda, \bar{\Lambda},$ and $K^0_S$ trigger particles and unidentified hadron associated particles are presented. The dependence of the near side peak on centrality and transverse momentum is investigated. Singly-strange triggers are compared to multiply-strange triggers and the Cu+Cu data are compared to the Au+Au data. These studies may help distinguish between particle production mechanisms. [Preview Abstract] |
Sunday, April 15, 2007 9:54AM - 10:06AM |
H15.00006: Study of jet quenching mechanisms at RHIC via multi-hadron correlations Jeremy Callner Recent experimental results from RHIC have shown that QCD jets created in ultra-relativistic heavy-ion collisions are quenched, depositing a significant fraction of their energy in the created strongly coupled medium. The details of the jet-quenching process are the subject of many theoretical predictions/calculations. Various energy loss scenarios have been proposed to explain experimental observations, such as the mach cone shock wave effect, Cherenkov gluon radiation, jet deflection in the expanding medium, and others. In this talk we will present a new three-particle correlation technique from STAR, in which we study the energy loss mechanisms in ultra-relativistic Au+Au collisions, particularly the deflection of the jets and the existence of a mach cone effect. We use a di-hadron projection of three-particle correlation on jet axis determined by two high-$p_{T}$ triggers. The measurements for Au+Au events of different centralities are compared with d+Au data used as a reference, unmodified by the QCD medium. [Preview Abstract] |
Sunday, April 15, 2007 10:06AM - 10:18AM |
H15.00007: Probing the hot medium using dihadron fragmentation functions in $Au-Au$ and $Cu-Cu$ collisions at $\sqrt{s_{NN}} = 200 GeV $ at RHIC Oana Catu One of the most important results from the experiments at RHIC is the observation of jet modification which is believed to be due to parton energy loss in heavy ion collisions. We present a detailed investigation of this effect using dihadron fragmentation functions measured using azimuthal correlations at high transverse momentum ($p_T$) . We study possible medium-modifications of the charge ordering in jets in heavy ion collisions by measuring the ratio of opposite-sign and same-sign pairs. The results are compared to Pythia calculations. This way we investigate the possible modification of charge ordering in jets in heavy ion collisions. We study the system size dependence of dihadron fragmentation functions by comparing the results for $Au-Au$ and $Cu-Cu$ collisions at $\sqrt{s_{NN}} = 200 GeV$ as measured in STAR. These results will give insight into the mechanisms of parton energy loss in the hot medium created in high energy heavy ion collisions at RHIC. [Preview Abstract] |
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