1. Measurements of J/   e + e - in Au+Au collisions at  s NN =200 GeV by PHENIX at RHIC Taku Gunji CNS, University of Tokyo For the PHENIX Collaboration 1 EB.7, Taku Gunji, DNP/JPS, Hawaii, 2005/09/21

2. Outline Physics Motivation PHENIX Detectors Data analysis Signal Counting Invariant Yield per binary collision R AA and theoretical models Invariant pT distribution Summary and Outlook 2

3. Physics Motivation Study the properties of hot and dense medium created by Heavy-Ion Collisions.  T, , , dof, collective behavior, deconfinement,,,, J/  measurement in Heavy-Ion Collisions  Suppression by Debye Color Screening Probe of de-confinement T. Mastui and H. Satz. PLB. 178 (1986) 416 Survive up to 2 Tc from recent lattice calculations  Enhancement by the recombination of uncorrelated cc pairs QGP phase + statistical coalescence at hadronization  Non-QGP effects Gluon shadowing Nuclear absorption Comover scattering 3 PHENIX d+Au J/  results show the nuclear absorption cross section is order1-3 mb. [nucl-ex/0507032]

4. PHENIX Experiment BBC, ZDC  centrality  z-vertex DC, PC1  momentum RICH  Electron ID EMCal (PbGl, PbSc)  Energy  Track Matching 4

5. Data analysis Invariant Yield Centrality selection  N evt Signal Counting of J/   N J/   e + e - Invariant mass  subtract combinatorial background Correction factors  single J/  detection efficiency   acc x  eff  centrality dependence   embed  Run-by-Run fluctuation of detector acceptance   run-by-run 5

6. Signal counting of J/  6 20-40%40-93% 209.0 +- 18.5 Analyzed 760 M Minimum Bias Data N J/  = N ee – N mixed_ee (2.9 <Mee<3.3 GeV)  Event mixing method was used. Invariant mass spectra Unlike pairs Mixed unlike pairs Central:0-20% Subtracted Centrality N J/  0-10% 145.4 +- 25.3 10-20% 155.1 +- 19.2 20-30% 124.2 +- 14.7 30-40% 87.9 +- 11.1 40-60% 70.1 +- 9.6 60-92% 26.7 +- 5.4 N J/   is counted in this mass range. Centrality vs. N J/ 

7. Invariant Yield per binary collisions BdN/dy per binary collisions (N binary )  6 centrality bins. (0-10/10-20/20-30/30-40/40-60/60-92%)  N binary from Glauber calculation. ( PRL. 91. 072301) Comparison to p+p & d+Au results. (nucl-ex/0507032)  (0.86 +- 0.10 ) x10 -6 (p+p), (0.79 +- 0.06 ) x 10 -6 in d+Au J/  yield is suppressed.  For more central collisions  Factor 3 of suppression for most central collisions. 0-10%: (0.279 +- 0.05)x10 -6 7 Binary scaling

8. R AA and theoretical models Consistent with nuclear absorption + shadowing (  abs ~ 3.0 mb) for centrality > 10% but Beyond the suppression for centrality 0-10%   abs ~ 3.0 mb seems to be high in d+Au data.   abs ~ 1.0 mb describes better d+Au results. Comover, direct dissociation and suppression in QGP over-predict the suppression 8 Suppression in QGP Nuclear absorption + Shadowing (EKS98)  abs  3.0 mb R. Vogt nucl-th/0507027 Comover scattering Direct dissociation Capella et.al. hep-ph/0505032 Grandchamp et.al. hep-ph/0306077 Kostyuk et.al. hep-ph/0305277

9. R AA and theoretical models Suppression + various recombination Models. Better matching with data points (at most central collisions) compared to the only suppression models. At RHIC (energy): Recombination compensates stronger QGP screening? 9 Suppression & Regeneration Regeneration Grandchamp et.al. hep-ph/0306077 private communication Statistic Coalescence Kostyuk et.al. hep-ph/0305277 Hadron-String Dynamics Bratkovskaya et.al. nucl-th/0402042 Grandchamp et.al. hep-ph/0306077 private communication

10. Invariant p T distribution 10 p+p d+Au Au+Au No recombination Recombination R.L. Thews et. al. nucl-th/0505055 Extraction of by fitting with p0(1+(p T /p1) 2 ) -6 Key to understand the recombination of J   No clear centrality dependence. Indication of recombination? Need to understand with rapidity dependence, charm production (pT etc).

11. Summary and Outlook Analyzed 760 M events (MB) of Au+Au collisions. Extracted Invariant yield per binary collisions  Factor 3 suppression for most central collisions. R AA was compared to theoretical models.  Consistent with normal nuclear absorption (  abs ~3.0) for >10% central  Suppression beyond nuclear absorption for 0-10% central.  Comover and QGP suppression over-predict the suppression.  Suppression + Recombination model matches better compared to the models with suppression-only. Extracted J/  p T distribution.  No clear centrality dependence. Recombination? Need to understand our data with:  d+Au results (but more statistic needed!)  Rapidity dependence (  Muon arm), Nuclear dependence (  Cu+Cu)  Charm production [thermalization, p T, rapidity] (  single e  single  11

12. Backup slides

13. Correction factors Single J/  detection efficiency  Full GEANT simulation of PHENIX detector  Same reconstruction code as used for real data Embedding efficiency  Centrality dependent efficiency  Simulated single J/   e+e- events were merged into real data. Run-by-Run efficiency  Evaluated by the yield of electron  Represent the normalization factor to the acceptance used in simulation 13  acc x  eff  embed

14. Correction factors -- run-by-run efficiency From Electron QA  Fluctuation of Relative to G9 14  RMS is assigned to systematic error.  Run-by-Run efficiency : 0.968 +- 0.001 (stat) +- 0.040(sys) [pro.59] 1.002 +- 0.004 (stat) +- 0.016(sys) [pro.66]

15. R AA and theoretical models Models using suppression + various regeneration mechanisms. Better matching with data points (at most central collisions) At RHIC: Recombination compensates stronger QGP screening? Energy density and gluon density at RHIC should be much higher (2-3 times) !? 15 Statistic Coalescence Hadron-String Dynamics Transport in QGP Suppression & Regeneration Regeneration Kostyuk et.al. hep-ph/0305277 Bratkovskaya et.al. nucl-th/0402042 Zhu et.al. nucl-th/0411093 Grandchamp et.al. hep-ph/0306077

16. Subtracted Mass distribution (0-10%, 10-20%, 0-20%) 0-10%10-20%0-20% 16 145.4 +- 25.3155.1 +- 19.2292.7 +- 31.9

17. Subtracted Mass distribution (20-30%, 30-40%, 20-40%) 17 20-30%30-40%20-40% 124.2 +- 14.787.9 +- 11.1 209.0 +- 18.5

18. Subtracted Mass distribution (40-60%, 60-92%, 40-92%) 16 40-60%60-92%40-92% 70.1 +- 9.6 26.7 +- 5.497.8 +- 11.0

19. Comparison of BdN/dy/N binary to NA50 19

20. J/  d+Au results 20

21. J / PSI PRODUCTION IN AU+AU COLLISIONS AT RHIC AND THE NUCLEAR ABSORPTION. By A.K. Chaudhuri (Calcutta, VECC),. Jul 2003. 4pp. e-Print Archive: nucl-th/0307029A.K. ChaudhuriCalcutta, VECC BASELINE COLD MATTER EFFECTS ON J/PSI PRODUCTION IN AA COLLISIONS. By R. Vogt (LBL, Berkeley & UC, Davis),. LBNL-58155, Jul 2005. 7pp. e-Print Archive: nucl-th/0507027R. VogtLBL, BerkeleyUC, Davis CHARM COALESCENCE AT RHIC. By A.P. Kostyuk, M.I. Gorenstein (Frankfurt U. & BITP, Kiev), Horst Stoecker, W. Greiner (Frankfurt U.),. May 2003. 4pp. Published in Phys.Rev.C68:041902,2003 e-Print Archive: hep-ph/0305277A.P. KostyukM.I. GorensteinFrankfurt U.BITP, KievHorst StoeckerW. GreinerFrankfurt U. CHARMONIUM CHEMISTRY IN A+A COLLISIONS AT RELATIVISTIC ENERGIES. By E.L. Bratkovskaya (Frankfurt U.), A.P. Kostyuk (Frankfurt U. & BITP, Kiev), W. Cassing (Giessen U.), Horst Stoecker (Frankfurt U.),. Feb 2004. 13pp. Published in Phys.Rev.C69:054903,2004 e-Print Archive: nucl-th/0402042E.L. BratkovskayaFrankfurt U.A.P. KostyukFrankfurt U.BITP, KievW. CassingGiessen U.Horst StoeckerFrankfurt U. MEDIUM MODIFICATIONS OF CHARM AND CHARMONIUM IN HIGH-ENERGY HEAVY ION COLLISIONS. By L. Grandchamp (LBL, Berkeley), R. Rapp (Texas A-M), G.E. Brown (SUNY, Stony Brook),. Mar 2004. 4pp. Talk given at 17th International Conference on Ultra Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California, 11-17 Jan 2004. Published in J.Phys.G30:S1355-S1358,2004 e-Print Archive: hep-ph/0403204L. GrandchampLBL, BerkeleyR. RappTexas A-MG.E. BrownSUNY, Stony Brook IN MEDIUM EFFECTS ON CHARMONIUM PRODUCTION IN HEAVY ION COLLISIONS. By Loic Grandchamp (SUNY, Stony Brook & Lyon, IPN), Ralf Rapp (Nordita), Gerald E. Brown (SUNY, Stony Brook),. Jun 2003. 4pp. Published in Phys.Rev.Lett.92:212301,2004 e-Print Archive: hep-ph/0306077Loic GrandchampSUNY, Stony BrookLyon, IPNRalf RappNorditaGerald E. BrownSUNY, Stony Brook J/PSI TRANSPORT IN QGP AND P(T) DISTRIBUTION AT SPS AND RHIC. By Xiang-lei Zhu, Peng-fei Zhuang (Tsinghua U., Beijing), Nu Xu (LBL, Berkeley),. Nov 2004. 6pp. Published in Phys.Lett.B607:107-114,2005 e-Print Archive: nucl-th/0411093Xiang-lei ZhuPeng-fei ZhuangTsinghua U., BeijingNu XuLBL, Berkeley ULTRARELATIVISTIC NUCLEUS-NUCLEUS COLLISIONS AND THE QUARK GLUON PLASMA. By A. Andronic, P. Braun-Munzinger (Darmstadt, GSI),. Feb 2004. 32pp. Lectures given at 8th Hispalensis International Summer School on Exotic Nuclear Physics, Seville, Spain, 9-21 Jun 2003. e-Print Archive: hep-ph/0402291A. AndronicP. Braun-MunzingerDarmstadt, GSI MOMENTUM SPECTRA OF CHARMONIUM PRODUCED IN A QUARK-GLUON PLASMA. By R.L. Thews (Arizona U.), M.L. Mangano (CERN),. CERN-PH-TH-2005-073, May 2005. 26pp. e-Print Archive: nucl-th/0505055R.L. ThewsArizona U.M.L. ManganoCERN PREDICTIONS FOR J / PSI SUPPRESSION BY PARTON PERCOLATION. By S. Digal, S. Fortunato (Bielefeld U.), H. Satz (CFIF, Lisbon),. BI-TP-2003-30, Oct 2003. 12pp. Published in Eur.Phys.J.C32:547-553,2004 e-Print Archive: hep-ph/0310354S. DigalS. FortunatoBielefeld U.H. SatzCFIF, Lisbon THE ONSET OF DECONFINEMENT IN NUCLEAR COLLISIONS. By H. Satz (Bielefeld U.),. May 1999. 15pp. Plenary talk given at 14th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (QM 99), Torino, Italy, 10-15 May 1999. Published in Nucl.Phys.A661:104-118,1999 e-Print Archive: hep-ph/9908339H. SatzBielefeld U. What do the Theorists Have to Say? 21