J/ y  e+e- measurements in √ s_{NN} = 200 GeV Au+Au collisions by PHENIX at RHIC

1. Poster # 187 J/y  e+e- measurements in √s_{NN} = 200 GeV Au+Au collisions by PHENIX at RHIC Results – BdN/dy/Ncol and RAA Subtracted Invariant Mass spectra NJ/y 1 dN B = 0-10% 10-20% 0-20% DyNcol x eacc xeembed xerun Nevt dyNcol NJ/y 1 dN 1 1 B = Dy DpT x eacc xeembed xerun Nevt pT p 2 p 2 dydpT pT • BdN/dy/Ncol • 6 centrality classes (0-10, 10-20, 20-30, 30-40, 40-60 and 60-92%) • BdN/dy/Ncol in p+p collisions and d+Au collisions (MB) are shown. • Bracket corresponds to systematic error. • dotted line corresponds to BdN/dy/Ncol in p+p collisions and its 1 sigma stat. error. • Observation of J/y suppression, especially for 0-10 and 10-20%. BdN/dy/Ncol (Npart) 145.4 +- 25.3 155.1 +- 19.2 292.7 +- 31.9 20-30% 30-40% 20-40% ( dNJ/y ( dsJ/y ) ) • RAA and Model comparison • Grey Band is the scale error that moves all the points up or down together. • Suppression factor ~ 2.5 at 0-10% central. • Comparison to the theoretical models RAA RAA (Npart) B B = 124.2 +- 14.7 87.9 +- 11.1 209.0 +- 18.5 dyNcol dy pT (GeV/c) 0.75 1.25 1.75 2.5 4.5 0.25 AuAu pp efficiency 1.00 % 0.82% 0.69% 0.54% 0.47% 0.91% 40-60% 60-92% 40-92% • Nuclear absorption • sabs =1.5, 3.0, 4.5, 7.1 mb centrality 0-10% 10-20% 20-30% 30-40% 40-60% 60-92% 1 efficiency 78.5 % 80.9% 86.5% 94.3% 95.2% 98.2% Comover scattering Capella et.al. hep-ph/0505032 sinelpp Direct dissociation Grandchamp et.al. hep-ph/0306077 70.1 +- 9.6 26.7 +- 5.4 97.8 +- 11.0 Suppression in QGP Kostyuk et.al. hep-ph/0305277 Kostyuk et.al. hep-ph/0305277 Statistic Coalescence A.Andronic et.al. nucl-th/0303036 Hadron-String Dynamics Central Arms Coverage (East and West) -0.35< y < 0.35, 30o <|f |< 120o Bratkovskaya et.al. nucl-th/0402042 Transport in QGP Zhu et.al. nucl-th/0411093 Suppression and Regeneration Grandchamp et.al. hep-ph/0306077 Regeneration • From the comparison to theoretical models • Consistent with the normal nuclear absorption (sabs = 3.0 +- 1.5 mb) for centrality > 20% and suppression beyond the nuclear absorption (sabs = 3.0 +- 1.5 mb) for centrality 0-10%. • Comover and Suppression in QGP over-predict the suppression. • Results of other models are consistent within the currect stat. and sys. error • Ring Imaging at RICH • 3.4 cm <r < 8.4 cm Energy- Momentum Matching at EMCal All charged tracks Electron BG RICH cut Taku Gunji, CNS, Univ. of Tokyo, for the PHENIX Collaboration J/y measurements in Heavy Ion Collisions “Signature of de-confined Quark-Gluon-Plasma” • J/y Suppression • Color Debye Screening in QGP • Melt from T>Tc • T. Matsui and H. Satz, Phys. Letr. B. 178, 416 (1986) • Survive up to T~2Tc (from Lattice calculation) • M. Asakawa and T.Hatsuda, Phys. Rev. Lett 92, 012001 (2004) • Nuclear Absorption • Nuclear dependence • SPS (NA38, NA50), Fermi Lab (E772) • Comover Scattering • Secondary interaction in hadronic phase • J/y enhancement • Recombination uncorrelated c and cbar • At RHIC, Ncc =10~ 20 @ central collision • Statistic Coalescence • formation of J/y at phase boundary • Detail balance • J/y + g  c + cbar Peripheral collisions Central collisions NA50 NA50, Phys. Lett. B477 (2000) 28. L.Grandchamp et al. : hep-ph/0306077 • Need to do systematic study of J/psi formation. • RAA vs. centrality • Shape of pT distribution (centrality dependence) • Nuclear Dependence (d-Au, Cu-Cu) • Energy dependence (200GeV, 62.4 GeV) • Rapidity dependence (PHENIX Muon arms) V. Tram(#171), M.Brooks(#130), M. Kweon(#139) K. Das(#181), D.Silvermyr(#208), A.Bickley(#129) Results – Invariant pT spectra R.L.Thews et.al. nucl-th/0505055 • Red triangle • initial production • Blue circles • in-medium recombination • <kT2> = 1.3 GeV2 • Green and Blue • pQCD charm distribution • Black • thermal + flow • T=128MeV. b=0.6 • Red • thermal + no flow • T=128 MeV. b=0 Summary and Outlook • First results of the centrality dependence of BdN/dy/Ncol and RAA • Consistent with the normal nuclear absorption (sabs = 3.0 +- 1.5) for >20% centrality and suppression beyond the normal nuclear absorption for 0-10% centrality. • Comover and Suppression in QGP over-predict the suppression at RHIC. • Results of other models are consistent within current stat. and sys. error. • First results of invariant J/y pT spectra (0-20, 20-40, 40-92%and MB). • No significant centrality dependence of <pT2> • Detail analysis with Muon results and Cu+Cu results. • Rapidity dependence and Nuclear dependence • J/y v2 measurement in Au+Au, Cu+Cu collisions • Need to understand the charm production in Heavy Ion Collisions • non-photonic electron v2 and spectrum • charm thermalization, charm pT distribution • Invariant pT spectra • Important measurement to understand the J/y formation scenarios. (suppression/recombination). • Suppression in QGP predicts larger <pT2>. • Recombination (charm thermalizetion) predicts smaller <pT2>. • But pT spectra have a dependence on charm pT distribution. • <pT2> vs. Npart was extracted for 0-20, 20-40, 40-92%, MB centrality classes. • First results at Mid-rapidity in Au+Au collisions at PHENIX. • Fitting was done with: A(1+(pT/B)2) -6, <pT2> = (B/2)2 • The result of <pT2> as a function of number of participants shows there is no clear Npart dependence of <pT2> with the current error bars. PHENIX Detectors Data Analysis A complex apparatus to measure:Hadrons, Muons, Electrons, Photons • PHENIX Year4 Au+Au Experiment • 1.6B events (240 mb-1 ) • 75% analyzed J/psi analysis • Optimized eID cut • Mixed event back ground • Signal counting (2.9<Mee<3.3 GeV) • Efficiency calculation by Simulation • pT dependence • centrality dependence • Centrality Measurement • Beam Beam Counter • Zero Degree Calorimeter • Momentum Measurement • Drift Chamber • Pad Chamber • Electron identification • Ring Imaging Cherenkov Counter • Number of Fired PMT • Ring Shape • Ring center Matching • Electro-Magnetic Calorimeter • E-p matching • Position Matching