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Measurement of Heavy Flavor Production in STAR Experiment at RHIC

Measurement of Heavy Flavor Production in STAR Experiment at RHIC. W. Xie for STAR Collaboration (Purdue University, West Lafayette).  l. Motivation for Studying Heavy Quarks. Heavy quark mass are external parameter to QCD. Sensitive to initial gluon density and gluon distribution.

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Measurement of Heavy Flavor Production in STAR Experiment at RHIC

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  1. Measurement of Heavy Flavor Production in STAR Experiment at RHIC W. Xie for STAR Collaboration (Purdue University, West Lafayette) Strong Interaction In The 21st Century, TIFR, 2010

  2. l Motivation for Studying Heavy Quarks • Heavy quark mass are external parameter to QCD. • Sensitive to initial gluon density and gluon distribution. • Interact with the medium differently from light quarks. • Suppression or enhancement pattern of heavy quarkonium production reveal critical features of the medium. • Cold Nuclear effect (CNM): • Different scaling properties in central and forward rapidity region CGC. • Gluon shadowing, etc K+ e-/- K- Non-photonic electron  D0 Open heavy flavor e-/- e+/+ Heavy quarkonia

  3. The larger the energy loss The smaller the RAA Some Variables to quantify the medium effect RAA ( or RdA) “no effect” No medium effect 5 N+N coll. in 1 A+A coll. • Heavy quarks are from Hard collision: • Each collision is separated clearly. • In the absence of any nuclear effect, • Yield(A+A) = yield(p+p)*N(collisions), i.e. scale with number of collisions (Ncoll)

  4. The STAR Detector MTD EMC barrel MRPC ToF barrel EMC End Cap FMS BBC FPD TPC FHC PMD Completed DAQ1000 HLT Ongoing R&D HFT FGT

  5. STAR hadrons pT> 6 GeV/c Measurements on Non-photonic Electron RAA • large suppression of heavy quark production is observed

  6. u u u light K+ c l l l D0 K+ Hot/Dense Medium c quark e-/- c D0 D0 meson energy loss Ivan, et al The Large Suppression was a Surprise K+ Hot/Dense Medium “dead cone effect”: gluon radiation suppressed at q< mQ/EQ c quark e-/- c D0 radiative energy loss (D. kharzeev, M.Djordjevicet al. ) Hot/Dense Medium c quark e-/- collision energy loss (Teany, Ralf, Denes et al.)

  7. Do we Understand the Result? PHENIX nucl-ex/0611018 STAR nucl-ex/0607012 • Radiative Energy Loss with reasonable gluon densities do not explain the observed suppression • Djordjevic, PLB632 81 (2006) • Armesto, PLB637 362 (2006) • Collisional EL may be significant for heavy quarks • Wicks, nucl-th/0512076 • Van Hess, PRC 73 034913 (2006) • Van Hess PRL 100, 192301(2008). • heavy quarks fragment inside the medium and are suppressed by dissociation? • Adil and Vitev, hep-ph/0611109 • Similar suppression for B and D at high-pT Possible Key to the solution: Separate charm and bottom measurements

  8. Disentangle Charm and Bottom Production B • wider φ distribution for B meson because of the larger mass. • Combined fit on data to obtain the B meson contribution to non-photonic electron. D X.Y. Lin, hep-ph/0602067

  9. Disentangle Charm and Bottom Production STAR preliminary JPG35(2008)104117 JPG35(2008)104117 • near side: mostly from B mesons • Away side: charm (~75%), Bottom (~25%)

  10. B Quark contribution is Significant Star preliminary Nuclear Physics A830 (2009)849c ~30-60% of non-photonic electron come from B meson decay.

  11. Disentangle Charm and Bottom Quark Energy Loss S. Sakai : SQM08 pT > 5 GeV/c I: Djordjevic et al, PLB 632 (2006) 81; dNg/dy = 1000 II: Adil et al, PLB 649 (2007) 139 III: Hees et al, PRL. 100 (2008) 192301

  12. c c d Quarkonia Suppression: “smoking gun” for QGP Physics Letter B Vol.178, no.4 1986 • Low temperature • Vacuum J/y • High temperature • High density • (screening effect take place) d D- D+ The melting sequence: cc -> Y’ -> J/y -> Upsilon

  13. c c c The life of Quarkonia in the medium can be complicated • Observed J/y is a mixture of direct production+feeddown. • All J/y ~ 0.6J/y(Direct) + ~0.3 cc + ~0.1y’ • Important to disentangle different component • Suppression and enhancement in the “cold” nuclear medium • Nuclear Absorption, Gluon shadowing, initial state energy loss, Cronin effect and gluon saturation (CGC) • Hot/dense medium effect • J/y,  dissociation, i.e. suppression • Recombination from uncorrelated charm pairs • Survival (or not) in the hot/dense medium from lattice calculation J/y D+

  14. Quarkonia Signals in STAR arXiv:1001.2745 STAR Preliminary STAR Preliminary STAR Preliminary STAR Preliminary STAR Preliminary • STAR can measure Quarkonia • of all different kind (,J/ψ, χc, …) • in all pT range. • at both mid and forward rapidity • in all collision species. forward J/ψ J/ψ from χc enriched

  15. J/y Production in 200GeV p+p collisions • Color singlet model (NNLO*CS): • P. Artoisenet et al., PRL. 101, 152001 (2008), and J.P. Lansberg private communication. • Include no feeddown from higher mass state. • LO CS+ color octet (CO): • G. C. Nayak et al., PRD 68, 034003 (2003), and private communication. • Include no feeddown from higher mass state. • Agree with the data • Color Evaporation Mode: • M. Bedjidian et al., hep-ph/0311048; R. Vogt private communication • Include feeddown from Xc and ψ’ • Agree with the data Phys.Rev.C80:041902,2009

  16. J/y-hadron Azimuthal Correlation in 200GeV p+p Collisions Phys.Rev.C80:041902,2009 • Constrain B meson yield through BJ/y: (13 ± 5) % of total J/y (pT>5GeV/c) • Constrain J/y Production mechanisms in p+p: • J/y+c, J/y+D or J/y+e • S. Brodsky, J.-P. Lansberg, arXiv:0908.0754

  17. J/y Suppression/enhancement in 200GeV A+A Collisions Au+Au Collisions: • Nice agreement with PHENIX Cu+Cu Collisions: • RAA(p>5 GeV/c) = 1.4± 0.4±0.2 • RAA seems larger at higher pT. • Model favored by data: • 2-component: nucl-th/0806.1239 • Incl. color screening, hadron phase dissociation, coalescence, B feeddown. • Model unfavored by the data: • AdS/CFT+Hydro: JPG35,104137(2008) • Comparison with open charm: • Charm quark & Heavy resonance : NPA784, 426(2007); PLB649, 139 (2007), and private communication Star preliminary Au+Au: 0-80% Phys.Rev.C80:041902,2009

  18.  Production in 200GeV p+p Collisions arXiv:1001.2745 arXiv:1001.2745 arXiv:1001.2745 pb

  19. RdAu ( ) in 200GeV d+Au Collisions NPA830(2009)235c NPA830(2009)235c nb

  20. Future of Heavy Flavor Measurement at STAR MTD (MRPC) Courtesy of T. Ullirich

  21. Examples of Future Measurements

  22. Summary and Perspective • Heavy flavor Studies at RHIC is at its early stage • Expecting exciting results in the coming years with upgraded detectors and luminosity.

  23. backup

  24. Non-photonic e-h correlations in Au+Au 200 GeV STAR Preliminary Au+Au: 0-20% 3 < pTtrig< 6 GeV/c && 0.15 < pTasso< 1.0 GeV/c

  25. Discrepancy between STAR and PHENIX • A factor of two difference between STAR and PHENIX • In high pT yield • Total cross section • in all collision species. • STAR New Measurements in p+p collision will come out soon.

  26. Forward Meson Spectrometer (FMS) • 20x more acceptance than previous forward detectors at STAR • Full azimuthal coverage for 2.5 < η < 4 FPD FMS • Increased acceptance not only increases pion yields and kinematic range but also gives much higher geometric efficiency for high-xF J/ψ Geometric Efficiency: J/ψ xF Chris Perkins

  27. Continuum contribution under Upsilon Peak

  28. D0 Signal

  29. J/y Suppression in Au+Au collisions CNM: sabs = 1-3 mb 1 RAA Bar: uncorrelated error Bracket : correlated error 0 1 RAA (1.2<|y|<2.2)/RAA (|y|<0.35) 0 • Larger suppression in forward rapidity comparing to midrapidity. • CNM suppression can not explain the results in Au+Au collisions

  30. NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) PHENIX at RHIC (1.2<|y|<2.2) NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) PHENIX at RHIC (1.2<|y|<2.2) NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) NA50 at SPS (0<y<1) NA50 (0<y<1) NA50 (0<y<1) NA50 (0<y<1) Bar: uncorrelated error Bracket : correlated error Global error = 12% and Global error = 7% are not shown Bar: uncorrelated error Bracket : correlated error Global error = 12% is not shown Normalized by NA51 p+p data with correction based on Eur. Phys. J. C39 (2005) : 355 Comparing RHIC to SPS Suppression results • After removing the CNM effect, differences start to show-up. • suppression at SPS consistent with the melting of psi’ and chi_c? • Need more precise d+Au measurements • Suppression pattern similar in RHIC and SPS. • CNM effect not removed yet.

  31. Do we understand J/y results Rapp direct Rapp direct Capella 1mb Capella 1mb Capella 3mb Capella 3mb Satz (w/ CNM) • Models that include only anomalous suppression predict too much suppression for RHIC mid-rapidity • Satz - color screening in QGP with CNM added (EKS shadowing + 1 mb) • Capella – comovers with normal absorption and shadowing • Rapp – direct production with CNM effects (without regeneration) • Models including both suppression and recombination match data better • R. Rapp(for y=0) PRL 92, 212301 (2004) • Thews (for y=0) Eur. Phys. J C43, 97 (2005) • Nu Xu et al. (for y=0) nucl-th/0608010 • Bratkovskaya et al. (for y=0) PRC 69, 054903 (2004) • A. Andronic et al. (for y=0) nucl-th/0611023 • All seems to be somewhat more consistent with the data. • Other sensitive comparisons are needed

  32. Flow of electrons from Charm and Bottom meson decay [Phys.Lett. B595 202-208 ] [PRC72,024906] [PRC73,034913] [PRB637,362] • Strong elliptic flow for non-photonic electron • Main source is D meson -> indicate non-zero D v2 • Charm v2 also non-zero ? • Bottom sneak in here?

  33. LO NLO NNLO PRL 101, 152001

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