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J/ y e + e - Measurement in Cu+Cu Collisions at RHIC-PHENIX. Susumu Oda CNS, University of Tokyo for the PHENIX Collaboration March 27th 2006 (Monday) 61st Annual Meeting of the Physical Society of Japan Ehime University. 1/10. 1. Physics Motivation.
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J/ye+e- Measurementin Cu+Cu Collisionsat RHIC-PHENIX Susumu Oda CNS, University of Tokyo for the PHENIX Collaboration March 27th 2006 (Monday) 61st Annual Meeting of the Physical Society of Japan Ehime University 1/10
1. Physics Motivation • Yields of heavy quarkonia are expected to be suppressed via color screening. • Measurement of quarkonia is one of the most promising probes for a hot and dense matter created in heavy ion collisions. • However, other competing effects influence quarkonia yields. • Cold matter effects (shadowing, nuclear absorption) • Recombination • Therefore, systematic study of quarkonia production is important. • Nuclear species : p+p, d+Au, Cu+Cu and Au+Au • Collision energy : 62.4 GeV and 200 GeV 2/10
2. PHENIX Experiment • Beam Beam Counter • Minimum bias trigger • Collision vertex • Centrality • Drift Chamber and Pad Chamber • Momentum • Ring Imaging Cherenkov • Electron ID • Electron trigger • EM Calorimeter • Energy • Track matching • Electron trigger • Muon Tracker • Muon Identifier 3/10
3. Invariant mass plotdi-electron channel Cu+Cu 200GeV : Jan. – Mar. 2005 Cu+Cu 62.4GeV : March 2005 J/y mass : 3.097 GeV/c2 J/ye+e- : BR 5.93 +/- 0.10 % J/ym+m- : BR 5.88 +/- 0.10 % Cu+Cu 62.4GeV 40 J/y’s Cu+Cu 62.4GeV Cu+Cu 200GeV 700 J/y’s Level-2 filtered data Full data production will start soon. Full data production finished last week. 4/10
5/10 4-1. Nuclear modification factor RAB • There is strong suppression beyond cold matter effects in central Cu+Cu and Au+Au collisions. deuteron gold PRL 96, 012304 (2006) |y|<0.35 ee 1.2<|y|<2.4 mm
6/10 4-1. Nuclear modification factor RAA Models that were successful in describing SPS data fail to describe data at RHIC. Recombination models agree with data much better.
7/10 2 without recombination with recombination 4-2. pT distribution • <pT2> was extracted by fittingwith A(1+(pT/B)2)-6 • Data seems to favor model with recombination. R.L. Thews et al. Cu+Cu 200GeV
8/10 4-3. Rapidity distribution • Recombination models expect rapidity shape to become narrower for increasing Npart. • No significant change in rapidity shape with centrality. R.L. Thews and M.L. Mangano Phys.Rev. C73 (2006) 014904 PHENIX Preliminary Cu+Cu 200GeV Au+Au 200GeV
5. Summary • PHENIX measured J/ydi-lepton in Cu+Cu, Au+Au, d+Au and p+p collisions. • Strong suppression beyond cold matter effects is obserbed. • Models that were successful in describing SPS data fail to describe data at RHIC. • Recombination agrees with observed suppression pattern and pT distribution. • However, expected rapidity shape change is not observed. 9/10 9/10
T.Frawley Heavy Flavor Productions and Hot/Dense Quark Matter Dec. 2005 6. Outlook • Proceed analysis and publish less systematic error result. • Other observables • J/y polarization • J/y hadron correlation • Elliptic flow of J/y • Reaction plane detector • Other heavy quarkonia • Feed down effect • y’J/y + anything (BR 58%) • ccgJ/y (BR 32%, 20%) • Different dissociation temperature • Ty’<Tcc<TJ/y • Bottomonium : U • RHIC-II : luminosity upgrade 10/10
