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Measurements of J/ y  e + e - in Au+Au collisions at s NN =200 GeV by PHENIX at RHIC

EB.7, Taku Gunji, DNP/JPS, Hawaii, 2005/09/21. 1. Measurements of J/ y  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. 2. Outline. Physics Motivation PHENIX Detectors Data analysis

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Measurements of J/ y  e + e - in Au+Au collisions at s NN =200 GeV by PHENIX at RHIC

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

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

  3. 3 Physics Motivation • Study the properties of hot and dense medium created by Heavy-Ion Collisions. • T, e, r, dof, collective behavior, deconfinement,,,, • J/y measurement in Heavy-Ion Collisions • Suppression by Debye Color Screening • Probe of de-confinementT. 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 PHENIX d+Au J/y results show the nuclear absorption cross section is order1-3 mb. [nucl-ex/0507032]

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

  5. 5 Data analysis • Invariant Yield • Centrality selection  Nevt • Signal Counting of J/y NJ/y • e+ e- Invariant mass • subtract combinatorial background • Correction factors • single J/y detection efficiency  eacc xeeff • centrality dependence  eembed • Run-by-Run fluctuation of detector acceptance  erun-by-run

  6. 6 Centrality NJ/y 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 Signal counting of J/y • Analyzed 760 M Minimum Bias Data • NJ/y = Nee – Nmixed_ee (2.9 <Mee<3.3 GeV) • Event mixing method was used. NJ/yis counted in this mass range. 20-40% 40-93% Invariant mass spectra Unlike pairs Mixed unlike pairs Subtracted Central:0-20% Centrality vs. NJ/y 209.0 +- 18.5

  7. 7 Invariant Yield per binary collisions • BdN/dy per binary collisions (Nbinary) • 6 centrality bins. (0-10/10-20/20-30/30-40/40-60/60-92%) • Nbinary 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/y yield is suppressed. • For more central collisions • Factor 3 of suppression for most central collisions. 0-10%: (0.279 +- 0.05)x10-6 Binary scaling

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

  9. 9 Suppression & Regeneration Statistic Coalescence Grandchamp et.al. hep-ph/0306077 private communication Kostyuk et.al. hep-ph/0305277 Hadron-String Dynamics Bratkovskaya et.al. nucl-th/0402042 Regeneration Grandchamp et.al. hep-ph/0306077 private communication RAA 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?

  10. 10 No recombination Recombination p+p d+Au Au+Au R.L. Thews et. al. nucl-th/0505055 Invariant pT distribution • Extraction of<pT2>by fittingwithp0(1+(pT/p1)2)-6 • Key to understand the recombination of J/y. • No clear centrality dependence. • Indication of recombination? • Need to understand with rapidity • dependence, charm production (pT etc).

  11. 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. • RAA was compared to theoretical models. • Consistent with normal nuclear absorption (sabs ~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/y pT 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, pT, rapidity] (single e, single m)

  12. Backup slides

  13. 13 Correction factors eacc xeeff • Single J/y detection efficiency • Full GEANT simulation of PHENIX detector • Same reconstruction code as used for real data • Embedding efficiency • Centrality dependent efficiency • Simulated single J/y  e+e- events were merged into real data. • Run-by-Run efficiency • Evaluated by the yield of electron • Represent the normalization factor to theacceptance used in simulation eembed

  14. 14 Correction factors -- run-by-run efficiency • From Electron QA • Fluctuation of <(Ne/Nevt)Eastx(Ne/Nevt)West> • Relative to G9 • 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. 15 RAA and theoretical models Statistic Coalescence • 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) !? Kostyuk et.al. hep-ph/0305277 Hadron-String Dynamics Bratkovskaya et.al. nucl-th/0402042 Transport in QGP Zhu et.al. nucl-th/0411093 Suppression & Regeneration Grandchamp et.al. hep-ph/0306077 Regeneration

  16. 16 Subtracted Mass distribution(0-10%, 10-20%, 0-20%) 0-10% 10-20% 0-20% 145.4 +- 25.3 155.1 +- 19.2 292.7 +- 31.9

  17. 17 20-30% 30-40% 20-40% 124.2 +- 14.7 87.9 +- 11.1 209.0 +- 18.5 Subtracted Mass distribution (20-30%, 30-40%, 20-40%)

  18. 16 40-60% 60-92% 40-92% 70.1 +- 9.6 26.7 +- 5.4 97.8 +- 11.0 Subtracted Mass distribution (40-60%, 60-92%, 40-92%)

  19. 19 Comparison of BdN/dy/Nbinary to NA50

  20. 20 J/y d+Au results

  21. 21 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.C68:041902,2003e-Print Archive: hep-ph/0305277 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.A661:104-118,1999e-Print Archive: hep-ph/9908339 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/0507027 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/0505055 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.C69:054903,2004e-Print Archive: nucl-th/0402042 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.B607:107-114,2005e-Print Archive: nucl-th/0411093 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/0402291 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/0307029 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.C32:547-553,2004e-Print Archive: hep-ph/0310354 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-S1358,2004e-Print Archive: hep-ph/0403204 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.92:212301,2004e-Print Archive: hep-ph/0306077 What do the Theorists Have to Say?

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