Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session S11: Mini-Symposium: Recent Results from RHIC I: Heavy Flavor |
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Sponsoring Units: DNP Chair: Huan Huang, University of California, Los Angeles Room: Maryland C |
Monday, February 15, 2010 3:30PM - 4:06PM |
S11.00001: Heavy Quarkonium Production at RHIC Invited Speaker: The dissociation of quarkonia due to color screening in a Quark-Gluon Plasma is a classic signature of de-confinement in relativistic heavy-ion collisions. Results at RHIC show that the suppression of the J/psi as a function of centrality (the number of participants) is similar to that observed at the SPS, even though the energy density reached in collisions at RHIC is significantly higher. Possible production mechanisms such as sequential suppression, $c\bar{c}$ recombination were proposed to explain this. In this talk, recent results of heavy quarkonia production in p+p and d+Au collisions at RHIC will be presented to understand quarkonia production mechanisms in hadron-hadron collisions and possible cold nuclear medium effect. The system size, rapidity, and pT dependence of heavy quarkonia production in Cu+Cu and Au+Au collisions will be reported to study the effect of color screening and their other possible production mechanisms. Future measurements with detector upgrades at RHIC will also be discussed. [Preview Abstract] |
Monday, February 15, 2010 4:06PM - 4:18PM |
S11.00002: Heavy quarkonia production in $p$+$p$ collisions at $\sqrt{s}$=200 GeV measured by PHENIX detector at RHIC Cesar L. da Silva Heavy quarkonia ($J/\psi$, $\psi^{\prime}$, $\chi_c$, $\Upsilon$, etc) has long been considered a sensitive probe of the confined and deconfined matter formed in heavy ion collisions due to its early formation, small size, strong binding and weak coupling relative to light mesons. The large mass of quarkonia compared to the QCD scale suggests the formation can be described in pQCD terms. However, the bound state formation can include non-perturbative contributions that are taken into account by different kinds of factorizations in the cross section calculation. Experimental observation of quarkonia yields, relative production of excited states and polarization in $p$+$p$ collisions are crucial tools to constrain the production mechanism models and are a reference when evaluating the nuclear modification factors in heavy ion collisions. The PHENIX collaboration at RHIC collected data in $p$+$p$ collisions at $\sqrt{s}$=200 GeV with a rapidity coverage of $|\eta|<0.35$ and $1.2<|\eta|<2.4$. This data allowed the observation of different quarkonia states by their di-lepton decay channels. We will report $J/\psi$, $\psi^{\prime}$, $\chi_c$, and $\Upsilon$ yields as well as $J/\psi$ polarization (spin alignment). The implications of these measurements towards the understanding of quarkonia formation, feed-down decay rates and comparison with results from other experimental facilities will be discussed. [Preview Abstract] |
Monday, February 15, 2010 4:18PM - 4:30PM |
S11.00003: J/$\psi$ suppression with respect to the reaction plane in Au+Au collisions at $\sqrt{s}$=200 GeV by the PHENIX detector Byungil Kim The possible formation of a QGP could affect how the initial anisotropy of particles in coordinate space is transferred into momentum space in the final state. Heavy quarkonia are produced dominatly by the gluon fusion at RHIC energy and should have less interactions than particles composed of light quarks. Hence, it would inherit the properties of the underlying heavy quarks and reflects its interaction with the medium, such as its elliptic flow and suppression with respect to the reaction plane. The measured reaction plane dependent J/$\psi$ yield would be used to determine the azimuthal dependence of the J/$\psi$ suppression as a function of $p_{T}$ and centrality, $R_{AA}$ ($p_{T}$, $\Delta\phi$). [Preview Abstract] |
Monday, February 15, 2010 4:30PM - 4:42PM |
S11.00004: $\Upsilon$ and $\chi_c$ production in $p$+$p$ and $d$+Au collisions at $\sqrt{s_{NN}}$=200 GeV in the PHENIX experiment Kwangbok Lee Quarkonia production is an important probe of the thermal properties of the quark-gluon plasma (QGP). Different quarkonia have different Debye screening lengths in the QGP, depending on their radii. As the energy density in the medium increases, quarkonia with smaller radii have a larger probability of survival. By measuring the relative yields of different quarkonia, we can quantitatively compare our experimental results to the theoretical predictions from finite temperature lattice QCD. And by measuring relative production in $p$+$p$ and $d$+Au collisions of $\Upsilon$ and $\chi_c$, we can have more probes to estimate cold nuclear effects such as shadowing, nuclear absorption, or interactions with comovers. We have performed simulation studies and data analysis for the $\Upsilon \rightarrow \mu^{+}+\mu^{-}$ and $\chi_c \rightarrow J/\psi + \gamma$ decay channels in $p$+$p$ and $d$+Au collisions at forward and backward rapidities. We use the PHENIX Muon Arms($1.2<|\eta|<2.2$) for the $\Upsilon$ measurement. Additionally, we use the Muon Piston Calorimeters(MPCs, $3.1<|\eta|<3.7$) for the $\chi_c$ measurement to detect the $\chi_c$ decay photon at very forward and backward rapidities. The status of simulation studies and data analysis for $\Upsilon$ and $\chi_c$ will be shown. [Preview Abstract] |
Monday, February 15, 2010 4:42PM - 4:54PM |
S11.00005: Upsilon + Hadron correlations at the Relativistic Heavy-Ion Collider (RHIC) Matthew Cervantes STAR has the capability to reconstruct the heavy quarkonium states of both the J/Psi and Upsilon particles produced by the collisions at the Relativistic Heavy Ion Collider (RHIC). The systematics of prompt production of heavy quarkonium is not fully described by current models, e.g. the Color Singlet Model (CSM) and the Color Octect Model. Hadronic activity directly around the heavy quarkonium has been proposed [1] as an experimental observable to measure the radiation emitted off the coloured heavy quark pair during production. Possible insight into the prompt production mechanism of heavy quarkonium can be obtained from this measured activity. Using STAR data from dAu collisions at sqrt(s{\_}NN)= 200 GeV, the high S/B ratio found in Upsilon reconstruction [2] can enable us to perform an analysis of Upsilon + Hadron correlations. We will present our initial investigation of such an analysis. \\[4pt] [1] Kraan, A. C., arXiv:0807.3123.\\[0pt] [2] Liu, H., STAR Collaboration, arXiv:0907.4538. [Preview Abstract] |
Monday, February 15, 2010 4:54PM - 5:06PM |
S11.00006: Measurement of single electrons from heavy flavor decays in d+Au collisions at $\surd $s = 200 GeV by PHENIX J. Matthew Durham Heavy quarks (c and b) produced in the early stages of heavy ion collisions carry valuable information about the dense partonic matter produced at RHIC. This information can be accessed through measurements of single electrons from semi-leptonic decays of these quarks. Present measurements in Au+Au collisions indicate a significant spectral modification as indicated by suppression at high transverse momentum. This measurement, along with significant azimuthal anisotropy, provides the most direct experimental evidence for the low viscosity of the matter formed in RHIC collisions. A full quantitative understanding of these phenomena requires experimental measurements of cold nuclear matter effects as inferred from single electron measurements in d+Au. The status of PHENIX measurements of single electrons from heavy flavor decays at mid rapidity from the 2008 RHIC d+Au run will be discussed. [Preview Abstract] |
Monday, February 15, 2010 5:06PM - 5:18PM |
S11.00007: Heavy flavor electron - hadron correlations in p+p and Au+Au collisions at PHENIX Jiayin Sun A surprising discovery at RHIC is the large suppression of heavy quarks in heavy ion collisions. Perturbative QCD predicted much less suppression for heavy mesons than $\pi^{0}$ mesons, however the measured suppression of charm and bottom quarks traversing Quark-Gluon Plasma from measurements is significantly larger than expected. Two particle correlations are used to study the propagation of hard partons traversing the hot matter produced by heavy ion collisions. Azimuthal correlations between electrons from decay of D and B mesons and charged hadrons are important measurements, for they provide additional information on how heavy quarks interact with the hot medium when compared with correlations of light hadrons. As a reference for heavy ion measurements, heavy flavor electron - hadron correlations are also measured for p+p collisions. We will present recent results of heavy flavor electron - hadron correlations for Au+Au and p+p collisions in the PHENIX experiment. [Preview Abstract] |
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