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This is a study on the production of heavy quarkonia in Cu+Cu collisions at RHIC-PHENIX. The measurements aim to explore color screening and other effects that may suppress quarkonia yields. The results show strong suppression beyond cold matter effects, and recombination models better describe the data than models successful at the SPS. The study also investigates pT and rapidity distributions of quarkonia. The outlook includes further analysis and observation of other heavy quarkonia as well.
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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
