Measurements of J/ e+e- in Au+Au collisions at sNN=200 GeV by

PHENIX at RHICTaku Gunji

CNS, University of TokyoFor the PHENIX Collaboration

1EB.7, Taku Gunji, DNP/JPS, Hawaii, 2005/09/21

Outline

Physics Motivation PHENIX Detectors Data analysisSignal Counting Invariant Yield per binary collisionRAA and theoretical models Invariant pT distribution Summary and Outlook

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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

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PHENIX d+Au J/results show the nuclear absorption cross section is order1-3 mb. [nucl-ex/0507032]

PHENIX Experiment

BBC, ZDC centrality z-vertex

DC, PC1 momentum

RICH Electron ID

EMCal (PbGl, PbSc) Energy Track Matching

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Data analysis Invariant Yield

Centrality selection Nevt

Signal Counting of J/ NJ/

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

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Signal counting of J/6

20-40% 40-93%

209.0 +- 18.5

Analyzed 760 M Minimum Bias Data NJ/ = Nee – Nmixed_ee (2.9 <Mee<3.3 GeV)

Event mixing method was used.Invariant mass spectraUnlike pairsMixed unlike pairs

Central:0-20%

Subtracted

Centrality NJ/ 0-10% 145.4 +- 25.310-20% 155.1 +- 19.220-30% 124.2 +- 14.730-40% 87.9 +- 11.1 40-60% 70.1 +- 9.660-92% 26.7 +- 5.4

NJ/is counted in this mass range.

Centrality vs. NJ/

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/ yield is suppressed. For more central collisions Factor 3 of suppression

for most central collisions.

0-10%: (0.279 +- 0.05)x10-6

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Binary scaling

RAA 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

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Suppression in QGP

Nuclear absorption +

Shadowing (EKS98) abs3.0 mb R. Vogt nucl-th/0507027

Comover scattering

Direct dissociationCapella et.al. hep-ph/0505032

Grandchamp et.al. hep-ph/0306077

Kostyuk et.al. hep-ph/0305277

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?

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Suppression & Regeneration

Regeneration

Grandchamp et.al. hep-ph/0306077 private communication

Statistic CoalescenceKostyuk et.al. hep-ph/0305277

Hadron-String DynamicsBratkovskaya et.al. nucl-th/0402042

Grandchamp et.al. hep-ph/0306077 private communication

Invariant pT distribution10

p+pd+AuAu+Au

No recombination

Recombination

R.L. Thews et. al. nucl-th/0505055

Extraction of <pT2> by fitting with p0(1+(pT/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).

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 (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 m

odels with suppression-only.

Extracted J/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 esingle

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Backup slides

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

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acc x eff

embed

Correction factors -- run-by-run efficiency

From Electron QA Fluctuation of <(Ne/Nevt)Eastx(Ne/Nevt)West>

Relative to G9

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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]

RAA 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) !?

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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

Subtracted Mass distribution(0-10%, 10-20%, 0-20%)

0-10% 10-20% 0-20%

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145.4 +- 25.3 155.1 +- 19.2 292.7 +- 31.9

Subtracted Mass distribution (20-30%, 30-40%, 20-40%)

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20-30% 30-40% 20-40%

124.2 +- 14.7 87.9 +- 11.1 209.0 +- 18.5

Subtracted Mass distribution (40-60%, 60-92%, 40-92%)

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40-60% 60-92% 40-92%

70.1 +- 9.6 26.7 +- 5.4 97.8 +- 11.0

Comparison of BdN/dy/Nbinary to NA50

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J/ d+Au results

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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

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

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/0305277

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/0402042

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/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.92:212301,2004 e-Print Archive: hep-ph/0306077

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/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

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

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/0310354

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/9908339

What do the Theorists Have to Say?21