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Heavy Flavor as a Probe of Quark-Gluon Plasma

Heavy Flavor as a Probe of Quark-Gluon Plasma. Pengfei ZHUANG Tsinghua University, Beijing. ● Charm Quark Thermalization ● J/ Ψ Regeneration in QGP ● Effect of Partonic Wind on Dihadron Correlation.

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Heavy Flavor as a Probe of Quark-Gluon Plasma

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  1. Heavy Flavor as a Probe of Quark-Gluon Plasma Pengfei ZHUANG Tsinghua University, Beijing ● Charm Quark Thermalization●J/Ψ Regeneration in QGP● Effect of Partonic Wind onDihadron Correlation with Li Yan, Xianglei Zhu of Tsinghua University, Nu Xu of LBNL, and Marcus Bleicher, Horst Stoecker of Frankfurt University Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

  2. Motivation Heavy quarks: Produced in initial impact and no extra production during the evolution,Produced via pQCD process, Sensitive probe of QGP and rather solid ground Heavy mesons: 10-20 c cbar pairs produced at RHIC energy even more than 100 pairs at LHC energy J/Ψ: (Thews et. al.) initial production, suppression, and regeneration Questions:1) are charm quarks thermalized in QGP? 2) Is J/  suppressed or enhanced? 3) are still back-to-back produced at RHIC and LHC? Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

  3. Theoretic Frame ●transverse transport equations in central rapidity region: : suppression in QGP relaxation time approximation, neglecting inelastic scatterings : regeneration in QGP ●J/Ψloss and gain terms via gluon dissociation perturbative calculation by Peskin, Bhanot … via detailed balance ●analytic solution pQCD distribution (Thews,…) thermal distribution initial production and nuclear absorption anomalous suppression regeneration Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

  4. Theoretic Frame ●1+2 dimensional ideal hydrodynamics for light quarks and gluons ●EoS(Sollfrank,…)ideal QGP phase and ideal hadron phase ●Initial condition of hydrodynamics:determined by nuclear geometry(Kolb, Heinz, Rapp,…) ●Parameters at RHIC ●D meson production Langevin equation for charm quark motion: Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

  5. Charm Quark Thermalization charm quark Pt distribution low Pt charm quarks are easily thermalized, but high Pt charm quarks are hard to get thermalized. pQCD thermal charm quark V2 decreasing D meson V2 at high Pt means non-thermalized high Pt charm quarks Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

  6. J/Ψ Regeneration in QGP Yan, Zhuang, Xu: PRL97,232301(2006) initial production still dominates the yield in semi-central collisions, but regeneration is definitely important in central collisions ! see also Rapp, Grandchamp, Brown, 2004, 2005 initially produced J/ψ are all eaten up by QGP, regeneration dominates J/ψbehavior at any centrality small V2 due to dominance of initial production Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

  7. Effect of Partonic Wind on Correlation Zhu, Bleicher, Huang, Schweda, Stoecker, Xu, Zhuang, PLB647, 366(2007) ● back-to-back production in hadron-hadron interaction ●what is the correlation at RHIC and LHC? ●hadronic re-scattering has little effects on correlation (UrQMD) ● how does the QGP modify the angular correlation? ●when charm quarks are thermalized, the collective expansion will push and to move in the same direction ! ●at RHIC, the back-to-back correlation is washed out by the partonic collectivity. ●at LHC, the NLO contribution, the fast thermalization of charm quarks, and the strong partonic wind change the production from back-to-back correlation to near side correlation ! Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

  8. Summary ● only low Pt charm quarks can be thermalized. ● J/Ψ: a smoking gun at LHC RHIC: both initial production and regeneration, still J/Ψ suppression and small V2LHC: almost only regeneration, J/Ψ enhancement and large V2 ● correlation: a sensitive signal of QGP RHIC: almost no correlation LHC: from back-to-back to near side correlation Pengfei ZHUANG INPC’07, Tokyo, June 3-8, 2007

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