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Study of Heavy-Flavor and Light-Flavor Thermalization at RHIC

Explore the collectivity and thermalization of heavy (c, b) and light (u, d, s) flavors at RHIC through multi-strange baryons, charm-quark flow, and more. Investigate the partonic EOS and probe thermalization using heavy-quarks. Analysis of particle freeze-out, constituent quark scaling, and the implications of heavy-flavor quarks in a QGP are discussed.

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Study of Heavy-Flavor and Light-Flavor Thermalization at RHIC

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  1. Heavy-Flavor (c,b) Collectivity – Light-Flavor (u,d,s) Thermalization at RHIC Kai Schweda, University of Heidelberg People: S. Blyth, X. Dong, Y. Lu, M. Oldenburg, H.G. Ritter, A. Rose, A. Shabetai, P. Sorensen, N. Xu, H. Zhang, Y. Zhang.

  2. Outline • Introduction • Multi-strange baryons elliptic flow • Charm-quark flow • Summary

  3. Quark Gluon Plasma Source: Michael Turner, National Geographic (1996) • Quark Gluon Plasma: • Deconfined and • thermalized state of quarks and gluons •  Study partonic EOS at RHIC(?) Probe thermalization using heavy-quarks

  4. Time Scale deconfinement u-, d-quarks and ‘bound-states’ gain mass Phase and Chiral transitions Coalescence processes occur during (phase) transition and hadronization; u-,d-quarks and ‘bound-states’ gain mass accompanied by expansion; Early thermalization with partons and its duration need to be checked.

  5. Kinetic Freeze-out 1) Compared to p, K, and p, multi-strange particles ,  are found at lower <T> but higher T ~ Tch  Collectivity prior to hadronization 2) Sudden single freeze-out*: Resonance decays lower Tfo for (p, K, p)  Collectivity prior to hadronization Partonic Collectivity ? STAR Preliminary Data: STAR preliminary Au+Au@200GeV: Nucl. Phys. A715, 129c(2003). *A. Baran, W. Broniowski and W. Florkowski; nucl-th/0305075

  6. Anisotropy Parameter v2 coordinate-space-anisotropy  momentum-space-anisotropy y py px x Initial/final conditions, EoS, degrees of freedom

  7. v2 in the Low-pT Region P. Huovinen, private communications, 2004 • Minimum bias data! At low pT, model result fits mass hierarchy well! • - Details does not work, need more flow in the model!

  8. Collectivity, Deconfinement at RHIC - v2, spectra of light hadrons and multi-strange hadrons - scaling with the number of constituent quarks At RHIC, it seems we have:  Partonic Collectivity • Deconfinement  Thermalization ? • PHENIX: PRL91, 182301(03) • STAR: PRL92, 052302(04) • S. Voloshin, NPA715, 379(03) • Models: Greco et al, PRC68, 034904(03) • X. Dong, et al., Phys. Lett. B597, 328(04). • ….

  9. Partonic Collectivity at RHIC • 1) Copiously produced hadrons freeze-out: • Tfo = 100 MeV, T = 0.6 (c) > T(SPS) • 2)Multi-strange hadrons freeze-out: • Tfo = 160-170 MeV (~ Tch), T = 0.4 (c) • 3)Multi-strange v2: • Multi-strange hadrons  and  do flow! • 4) Constituent Quark scaling: • Seems to work for v2 and RAA (RCP) • Deconfinement & • Partonic (u,d,s) Collectivity!

  10. Heavy-Flavor Quarks • Symmetry is broken: QCD dynamical mass EW Higgs mass • Even in a QGP, charm and beauty quark-mass heavy ! • Charm(Beauty) good probe for medium created at RHIC • If heavy quarks flow:  frequent interactions among all quarks light quarks (u,d,s) likely to be thermalized 106 105 104 103 102 10 1 Mass (MeV/c2) Plot: B. Mueller, nucl-th/0404015. Plot: B. Mueller, nucl-th/0404015.

  11. Charm-quark Elliptic Flow • Coalescence approach • AMPT transport model V. Greco et al., PLB 595(2004)202 B. Zhang et al., nucl-th/0502056 Large X-sec needed to reach large v2 → Charm quark flows → Indication of light flavor thermal equilibrium! Theoretical justification of the large cross section?

  12. V. Greco et al. PLB 595(2004)202 B. Zhang et al. nucl-th/0502056 Non-photonic electron v2 c (b)  e + X • Experimental data do not agree at 2<pT(e)<5 GeV/c! • v2(e) favors non-zero v2(c) at pT(e)<2 GeV/c.

  13. Open Charm Flow • Two extreme scenarios: • (a) No charm quark flow (PYTHIA) • (b) Charm quark flow (Hydro) •  Differences in D-meson spectra ~30% at pT < 2.0 GeV/c • D  e + X: electron spectra undistinguishable ! • Information on charm-dynamics washed out • Need direct open charm reconstruction to low pT! S. Batsouli et al., Phys. Lett. B 557 (2003) 26.

  14. Counts AuAu 200 GeV min.bias S/B = 1 : 1000 D0 - Spectra • D0 K + p • d+Au : no flow • Au+Au: charm-quark flow, b = 0.4c ? • Differences in spectra: 50% • Need precise (direct) measurement • TPC (+TOF): - large combinatorial backgrd.- large syst. uncertainties (30%) • Use decay topology Data: STAR, Phys. Rev. Lett. 94, 062301.Also: H. van Hees and R. Rapp, Phys. Rev C71, 034907.

  15. STAR Detector Upgrade Full Barrel MRPC - TOF Heavy Flavor Tracker • D0 K + p, ct = 123mm • Measure decay vertex, s 50mm • enhance S/B by factor 100 •  precise heavy-flavor measurements !

  16. Summary • Multi-strange hadrons  and  flow Partonic collectivity • Measure spectra, elliptic flow and yields of D0, D, D+s, L+C Probe (u,d,s)-quark thermalization • STAR upgrade TOF + mVertex

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