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Chinese New Year Feb. 7. 2008 Happy New Year Eve! Happy Mouse Year!

This presentation provides an overview of charm production and measurements at RHIC, including signal/spectra, flow and energy loss, and correlations. The importance of studying charm in understanding the properties of hot-dense matter is highlighted. The results from STAR and PHENIX experiments are presented, along with theoretical calculations and future outlook.

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Chinese New Year Feb. 7. 2008 Happy New Year Eve! Happy Mouse Year!

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  1. Chinese New Year Feb. 7. 2008 Happy New Year Eve! Happy Mouse Year!

  2. Overview of Charm production at RHIC Yifei Zhang University of Science & Technology of China Thanks to: The conference organizers Quark Matter 2008, Feb. 4-10, Jaipur, India Yifei ZhangUSTC

  3. Outline • Introductions • Signal/Spectra • Flow & energy loss • Correlations • Summary & Outlook Yifei ZhangUSTC

  4. Why measure charm? Mb 4.8 GeV >> Tc, LQCD, Muds Mc 1.3 GeV • Higgs mass: electro-weak symmetry breaking. (current quark mass) • QCD mass: Chiral symmetry breaking. (constituent quark mass) • Heavy quark masses are not modified by QCD vacuum. Strong interactions do not affect them. • Important tool for studying properties of the hot-dense matter created at RHIC energy. Muller nucl-th/0404015 Yifei ZhangUSTC

  5. Charm production cross-section • Charmquarks are believed to be mainly produced at early stage by initial gluon fusions. • Sensitive to initial parton distribution function. • Nuclear and medium properties at initial stage. • Precondition for light flavor thermalization if charm flow.. • Essential for recombination calculations of J/ production. M. Gyulassy & Z. Lin, PRC 51 (1995) 2177 Npart L.Yan, P.Zhuang, N.Xu PRL 97 (2006) 232301 PHENIX data nucl-ex/0611020 Yifei ZhangUSTC

  6. Charm measurements at RHIC STAR measurements: • Signal/Spectra D0 K • c   + X (y=0, low pT) • c  e + X • Flow & energy loss Radial flow from NPE RAA from NPE • Correlations D*-jet, e-h, e-D0 PHENIX measurements: • Signal/Spectra D0 K-+0 • c   + X (<y>=1.65, pT>1 GeV/c) • c  e + X • e+e- • Flow & energy loss Elliptic flow from NPE RAA from NPE • Correlations e-h Yifei ZhangUSTC

  7. Outline • Introductions • Signal/Spectra • Flow & energy loss • Correlations • Summary & Outlook Yifei ZhangUSTC

  8. D0 Phys. Rev. Lett. 94 (2005) Direct D-meson reconstructions at STAR STAR Preliminary Section XIV: A. Shabetai K invariant mass distribution in d+Au, Au+Au minbias, Cu+Cu minbias at 200 GeV collisions. Yifei ZhangUSTC

  9. S. Butyk (LANL) PHENIX Preliminary Year5 pp 200 GeV Direct D-meson reconstruction at PHENIX Reconstruct D0K+p-p0 decay in pp p0 identified via p0 gg decay Y. Akiba Heavy Quark Workshop Yifei ZhangUSTC

  10. Lepton from HF decay at STAR STAR Preliminary New Cu+Cu D0 spectrum agree with Au+Au after number of binary scaled. Low pT muon constrains charm cross-section. Yifei ZhangUSTC

  11. Lepton from HF decay at PHENIX PHENIX PRL, 98, 172301 (2007) PHENIX Preliminary Y. Akiba heavy quark workshop Section XIV: D. Hornback Electron spectrum is harder than muon spectrum, within errors they are consistent at intermediate pT. Systematically higher than FONLL calculation. Integral e yield follows binary scaling, high pT strong suppression at central AuAu collisions. Yifei ZhangUSTC

  12. c dominant b dominant Heavy Quarks in p+p from e+e- at PHENIX After subtraction of Cocktail - Fit to a*charm+ b*bottom (with PYTHIA shape) Good agreement with single e result. arXiv:0802.0050 Plenary III: T. Awes Yifei ZhangUSTC

  13. Charm cross-section PRL 94 (2005) Section XIV: D. Hornback Total cross-section with large theoretical uncertainty. Section XIV: A. Shabetai Both STAR and PHENIX are self-consistent. STAR results ~ 2 times larger than PHENIX Consistent with NLO calculation. Yifei ZhangUSTC

  14. Outline • Introductions • Signal/Spectra • Flow & energy loss • Correlations • Summary & Outlook Yifei ZhangUSTC

  15. Radial flow – lepton from HF decays D0 STAR Preliminary STAR Preliminary Tfo = 220 MeV (best fit) – freeze out ealier <t> = 0.23 (best fit), <0.42 (1-). favor moderate or small radial flow. -- dense medium, light flavor thermalization. Yifei ZhangUSTC

  16. Elliptic flow v2 – NPE from HF decays PHENIX Run4 PRL, 98, 172301 (2007) Poster: A.Dion Non-zero elliptic flow for electron from heavy flavor decays → indicatesnon-zero D v2,partonic level collective motion. Strongly interact with the dense medium at early stage of HI collisions. Light flavor thermalization. Yifei ZhangUSTC

  17. STAR PRL, 98, 192301 (2007) PHENIX PRL, 98, 172301 (2007) Radiative + Collisional eloss calculations describe data better. Question: Partonic eloss mechanism? Bottom contribution? Charm energy loss, unsolved puzzle No direct D-meson measurement at high pT. Heavy flavor electron suppression was observed in several experiments. STAR and PHENIX are consistent with each other. Yifei ZhangUSTC

  18. Outline • Introductions • Signal/Spectra • Flow & energy loss • Correlations • Summary & Outlook Yifei ZhangUSTC

  19. D* in jet and gluon splitting Poster: X. Dong STAR Preliminary STAR Preliminary Data consistent with pQCD calculation for gluon splitting rate. Wrong sign and side band describe the background well. Clear D* signal is seen. Compare to NLO cal., gluon splitting to total charm production at RHIC is small. Yifei ZhangUSTC

  20. e-h correlations – conical emission Trigger on NPE from heavy quark decays. Section XIII: G. Wang Au+Au 200 GeV Cu+Cu 200 GeV STAR Preliminary Does heavy quark e-loss generate Mach Cone emission? Yifei ZhangUSTC

  21. e-h correlations – bottom contribution Session XIV: Y. Morino Section XIII: G. Wang Simulation: ce, be, c+be Extract b/c ratio from the data/simulation comparison Yifei ZhangUSTC

  22. e-h correlations – bottom contribution (be)/(ce+be) Section XIII: G. Wang Section XIV: A. Mischke Session XIV: Y. Morino Good agreement among different analyses. Data consistent with FONLL. Yifei ZhangUSTC

  23. Does bottom affect charm X-sec? STAR Preliminary Before subtraction: (AuAu MB) (AuAu 0-12%) After bottom contribution subtraction: (AuAu MB) (AuAu 0-12%) Bottom contribution does NOT change charm cross-section (be)/(b+ce) upper limit of NLO is applied Yifei ZhangUSTC

  24. Summary • Charm cross-section is found to follow number of binary collisions scaling, STAR and PHENIX are not consistent with each other. • None zero charm flow is observed at RHIC energy. • Electron suppression is observed at RHIC but the energy loss mechanism is still NOT really understood. • Abounding correlations related to heavy flavor are reported. Yifei ZhangUSTC

  25. Outlook Charm is charming, since there are lots of things unknown! Both STAR and PHENIX are upgrading! LHC is coming! We will have a bright future! THANK YOU! Yifei ZhangUSTC

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