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

2. 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 D0D0 K+K+  l K-K- e-/-e-/- e-/-e-/- e+/+e+/+ Heavy quarkonia Open heavy flavor 2 Non-photonic electron

3. Some Variables to quantify the medium effect 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) “no effect” R AA ( or R dA ) No medium effect The larger the energy loss The smaller the R AA 5 N+N coll. in 1 A+A coll. 3

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

5. Measurements on Non-photonic Electron R AA large suppression of heavy quark production is observed STAR hadrons p T > 6 GeV/c 5

6. The Large Suppression was a Surprise D0D0 radiative energy loss c quark K+K+ l e-/-e-/- light (D. kharzeev, M.Djordjevic et al. ) u c “dead cone effect”: gluon radiation suppressed at  < m Q /E Q collision energy loss c quark Hot/Dense Medium (Teany, Ralf, Denes et al.) D0D0 K+K+ l e-/-e-/- D0D0 meson energy loss c quark u c Hot/Dense Medium Ivan, et al u c D0D0 K+K+ l e-/-e-/- 6

7. Do we Understand the Result? 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-p T PHENIX nucl-ex/0611018 STAR nucl-ex/0607012 7 Possible Key to the solution: Separate charm and bottom measurements

8. 8/18 Disentangle Charm and Bottom Production 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. B D X.Y. Lin, hep-ph/0602067

9. 9/18 Disentangle Charm and Bottom Production near side: mostly from B mesons Away side: charm (~75%), Bottom (~25%) STAR preliminary JPG35(2008)104117

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

11. 11/18 Disentangle Charm and Bottom Quark Energy Loss I: Djordjevic et al, PLB 632 (2006) 81; dN g /dy = 1000 II: Adil et al, PLB 649 (2007) 139 III: Hees et al, PRL. 100 (2008) 192301 p T > 5 GeV/c S. Sakai : SQM08

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

13. The life of Quarkonia in the medium can be complicated Observed J/  is a mixture of direct production+feeddown. – All J/  ~ 0.6J/  (Direct) + ~0.3  c + ~0.1  ’ 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/   dissociation, i.e. suppression – Recombination from uncorrelated charm pairs –Survival (or not) in the hot/dense medium from lattice calculation D+D+ cc c J/  13

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

15. 15 J/  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. 16 J/  -hadron Azimuthal Correlation in 200GeV p+p Collisions  Constrain B meson yield through B  J/  (13 ± 5) % of total J/  (pT>5GeV/c)  Constrain J/  Production mechanisms in p+p:  J/  +c, J/  +D or J/  +e  S. Brodsky, J.-P. Lansberg, arXiv:0908.0754 Phys.Rev.C80:041902,2009

17. 17 J/  Suppression/enhancement in 200GeV A+A Collisions Au+Au Collisions: Nice agreement with PHENIX Cu+Cu Collisions:  R AA (p  >5 GeV/c) = 1.4± 0.4±0.2  R AA 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 Au+Au: 0-80% Phys.Rev.C80:041902,2009 Star preliminary

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

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

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

21. 21 Examples of Future Measurements

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

23. backup 23

24. Au+Au: 0-20% 3 < p T trig < 6 GeV/c && 0.15 < p T asso < 1.0 GeV/c 24/18 STAR Preliminary Non-photonic e-h correlations in Au+Au 200 GeV

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. 25

26. 3/31/2009Chris Perkins26 Forward Meson Spectrometer (FMS) 20x more acceptance than previous forward detectors at STAR Full azimuthal coverage for 2.5 < η < 4 FPD FMS Geometric Efficiency: J/ψ x F Increased acceptance not only increases pion yields and kinematic range but also gives much higher geometric efficiency for high-x F J/ψ

27. Continuum contribution under Upsilon Peak

28. 28 D 0 Signal

29. 29

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

31. Comparing RHIC to SPS Suppression results NA50 at SPS (0<y<1) Normalized by NA51 p+p data with correction based on Eur. Phys. J. C39 (2005) : 355 NA50 (0<y<1) NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) Bar: uncorrelated error Bracket : correlated error Global error = 12% is not shown NA50 (0<y<1) NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) PHENIX at RHIC (1.2<|y|<2.2) Bar: uncorrelated error Bracket : correlated error Global error = 12% and Global error = 7% are not shown NA50 (0<y<1) Suppression pattern similar in RHIC and SPS. CNM effect not removed yet. NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) PHENIX at RHIC (1.2<|y|<2.2) 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

32. 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 Do we understand J/  results Rapp direct Capella 1mb Capella 3mb Satz (w/ CNM) Rapp direct Capella 1mb Capella 3mb

33. Flow of electrons from Charm and Bottom meson decay Strong elliptic flow for non-photonic electron Main source is D meson -> indicate non-zero D v 2 Charm v 2 also non-zero ? Bottom sneak in here? [Phys.Lett. B595 202-208 ] [PRC72,024906] [PRC73,034913] [PRB637,362]

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35. 35 LO NLO NNLO PRL 101, 152001