1. Quarkonium Workshop, BNL, June 6-18, 2011 1 Zebo Tang @ USTC Zebo Tang (for the STAR Collaboration) University of Science and Technology of China (USTC) J/  measurements at STAR

2. Quarkonium Workshop, BNL, June 6-18, 2011 2 Zebo Tang @ USTC Motivation J/  production in A+A collisions: Quarkonium only known probe to test deconfinement Color screening in deconfined medium Charm quark coalescence/recombination Formation time effect at high-p T Experimental measurements in different centralities: Spectra and radial flow Nuclear modification factor Elliptic flow J/  production in p+p collisions: Baseline for A+A Provide insight in production mechanism (Color-singlet vs. Color-octet) Establish/Estimate feeddown Experimental measurements: J/  spectra J/  -hadron correlation

3. Quarkonium Workshop, BNL, June 6-18, 2011 3 Zebo Tang @ USTC Previous measurements at STAR STAR, PRC80, 041902(R), 2009 Spectra harder than CSM Leave no room for feeddown in COM First J/  -hadron correlation in p+p at RHIC  First estimation of B  J/  feeddown No suppression at high-p T in Cu+Cu collisions

4. Quarkonium Workshop, BNL, June 6-18, 2011 4 Zebo Tang @ USTC STAR detector 2  coverage at mid-rapidity (|  |<1) TPC+BEMC+(MRPC-TOF)+(HLT) in this analysis

5. Quarkonium Workshop, BNL, June 6-18, 2011 5 Zebo Tang @ USTC Electron identification (TPC only) With TPC only: Difficult electron ID at low p T and high p T Possible to get an electron sample with reasonable purity at intermediate p T x sigma deviation from electron dE/dx curve Note: electron yield is much less than hadrons

6. Quarkonium Workshop, BNL, June 6-18, 2011 6 Zebo Tang @ USTC Electron ID (TPC+TOF) dE/dx after TOF cut Overall efficiency ~ 60%

7. Quarkonium Workshop, BNL, June 6-18, 2011 7 Zebo Tang @ USTC Electron ID (BEMC) Online fast trigger: Enhance high p T electron Enhance recorded luminosity Offline cuts: Matching between EMC and TPC Deposited energy (BTOW) Shower shape (BSMD)  x  0.05x0.05) ~5X 0 High p T J/  high p T electron (TPC+EMC) + Low/Intermediate p T electron (TPC only or TPC+TOF)

8. Quarkonium Workshop, BNL, June 6-18, 2011 8 Zebo Tang @ USTC High-p T J/  signals p+p, 2009 TPC+BEMC for spectra TPC+BEMC+TOF for correlation TPC+BEMC+TOF Significantly reduced material in 2009 p+p and 2010 Au+Au collisions Clear signal in both p+p and Au+Au collisions High Signal/Background ratio in p+p allows correlation study

9. Quarkonium Workshop, BNL, June 6-18, 2011 9 Zebo Tang @ USTC J/  spectra in 200GeV p+p collisions Consistent with previous results Good agreement between STAR and PHENIX Color singlet model: direct NNLO still misses the high-p T part P. Artoisenet et al., Phys. Rev. Lett. 101, 152001 (2008), and J.P. Lansberg private communication. LO CS+CO: leave no room for feeddown at high p T G. C. Nayak, M. X. Liu, and F. Cooper, Phys. Rev. D68, 034003 (2003), and private communication. Tsallis Blast-Wave model: ZBT et al., arXiv:1101.1912; JPG 37, 085104 (2010) PHENIX: Phys. Rev. D 82, 012001 (2010) STAR: Phys. Rev. C80, 041902(R) (2009) CEM can reasonably explain the spectra M. Bedjidian et al., hep-ph/0311048, and R. Vogt private communication

10. Quarkonium Workshop, BNL, June 6-18, 2011 10 Zebo Tang @ USTC J/  -hadron correlations

11. Quarkonium Workshop, BNL, June 6-18, 2011 11 Zebo Tang @ USTC PRC80, 041902(R), 2009 PLB370, 239, 1996 PLB200, 380, 1988 PRD71, 032001, 2005 EPJC71, 1575, 2011 (B  J/  / (inclusive J/  Extracted from near side J/  -h correlation Consistent with previous results No significant beam energy dependence Can be used to constrain B production R. Vogt, Workshop on Heavy Quark Production in Heavy-ion Collisions, Jan. 6, 2011, Purdue University

12. Quarkonium Workshop, BNL, June 6-18, 2011 12 Zebo Tang @ USTC Away side associated hadron p T spectra Consistent with hadron-hadron correlation  away-side seems to come from gluon/light quark fragmentation STAR, PRL95, 152301 (2005)

13. Quarkonium Workshop, BNL, June 6-18, 2011 13 Zebo Tang @ USTC J/  spectra in 200GeV Au+Au collisions Good agreement between STAR and PHENIX Significantly extend the p T range to 10 GeV/c J/  spectra significantly softer than the prediction from light hadrons  Much smaller radial flow?  Regeneration at low p T ? Tsallis Blast-Wave model: ZBT et al., arXiv:1101.1912; JPG 37, 085104 (2010) Phys. Rev. Lett. 98, 232301 (2007)

14. Quarkonium Workshop, BNL, June 6-18, 2011 14 Zebo Tang @ USTC R AA vs. p T Increase from low p T to high p T Consistent with unity at high p T in (semi-) peripheral collisions More suppression in central than in peripheral even at high p T STAR CuCu: PRC80, 014922(R) PHENIX: PRL98, 232301 Yunpeng Liu, Zhen Qu, Nu Xu and Pengfei Zhuang, PLB 678:72 (2009) and private comminication Xingbo Zhao and Ralf Rapp, PRC 82,064905(2010) and private communication

15. Quarkonium Workshop, BNL, June 6-18, 2011 15 Zebo Tang @ USTC R AA vs. Npart Systematically higher at high p T in all centralities Suppression in central collisions at high p T System size dependent due to J/  formation time effect? Escaping at high p T (without jet quenching effect)? Yunpeng Liu, Zhen Qu, Nu Xu and Pengfei Zhuang, PLB 678:72 (2009) and private comminication Xingbo Zhao and Ralf Rapp, PRC 82,064905(2010) and private communication STAR Pion: Yichun Xu at QM2009

16. Quarkonium Workshop, BNL, June 6-18, 2011 16 Zebo Tang @ USTC Comparison All suppressed in central heavy-ion collisions!! Similar suppression for STAR high-p T J/  and Upsilon Stronger suppression for high-p T J/  at CMS than at RHIC  Different rapidity range! Different p T range vs. beam energy! See Rosi Reed’s talk for Upsilon results

17. Quarkonium Workshop, BNL, June 6-18, 2011 17 Zebo Tang @ USTC J/  elliptic flow v 2 [1] V. Greco, C.M. Ko, R. Rapp, PLB 595, 202. [2] L. Ravagli, R. Rapp, PLB 655, 126. [3] L. Yan, P. Zhuang, N. Xu, PRL 97, 232301. [4] X. Zhao, R. Rapp, 24th WWND, 2008. [5] Y. Liu, N. Xu, P. Zhuang, Nucl. Phy. A, 834, 317. [6] U. Heinz, C. Shen, priviate communication. Hao Qiu, QM2011 Consistent with zero Disfavor coalescence from thermalized charm quarks No regeneration? Regeneration only at low p T ? Charm does not flow? STAR Preliminary

18. Quarkonium Workshop, BNL, June 6-18, 2011 18 Zebo Tang @ USTC Summary  In p+p collisions J/  spectrum measurements are extended to high p T Large S/B ratio allows correlation study B has sizeable (not dominant) contribution at high p T High-p T J/  away side hadron production consistent with gluon / light quark fragmentation  In heavy-ion collisions Observation of no suppression for J/  at high p T (5-10 GeV/c) at STAR in 200GeV Cu+Cu and peripheral Au+Au collisions, And suppression at high p T in central Au+Au collisions J/  suppression at high p T less than that at low p T J/  v 2 measurements are consistent with zero, disfavor coalescence from thermalized charm quarks J/  spectra and v 2 are consistent with J/  not participating in bulk flow

19. Quarkonium Workshop, BNL, June 6-18, 2011 19 Zebo Tang @ USTC High-p T J/  in d+Au 420 signals 13  ZBT, QM2009 Significant signal Study CNM effect at high p T

20. Quarkonium Workshop, BNL, June 6-18, 2011 20 Zebo Tang @ USTC 82±13 6  J/  in Au+Au @ BES Clear signals seen in both 39 GeV and 62 GeV Au+Au collisions Reference data available from Fermi Lab Experiments and ISR 62 GeV Au+Au EMC Trigger 39 GeV Au+Au EMC Trigger 39 GeV Au+Au Min. Bias Trigger

21. Quarkonium Workshop, BNL, June 6-18, 2011 21 Zebo Tang @ USTC Muon Telescope Detector (MTD) Advantages over electrons no  conversion much less Dalitz decay contribution less affected by radiative losses in the materials Trigger capability for low to high p T J/  in central Au+Au collisions High  /hadron enhancement S/B~2 in central Au+Au Lijuan Ruan, QM2011

22. Quarkonium Workshop, BNL, June 6-18, 2011 22 Zebo Tang @ USTC MTD in RHICII era J/  MTD+HFT: Trigger and topologically reconstruct B  J/  MTD+TOF: J/  +ccbar? Charmonium higher states? Υ Thank you!

23. Quarkonium Workshop, BNL, June 6-18, 2011 23 Zebo Tang @ USTC backup

24. Quarkonium Workshop, BNL, June 6-18, 2011 24 Zebo Tang @ USTC Sequential dissociation? Npart/2 J/  spectra are modified in medium in Au+Au collisions Spectra does not support scenario of large radial flow R AA of high-p T J/  and Upsilon similar (poster: Rosi Reed for STAR) J/  v 2 consistent with zero, calescence from thermalized charm quarks unlikely

25. Quarkonium Workshop, BNL, June 6-18, 2011 25 Zebo Tang @ USTC