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J/ y production in Au+Au and Cu+Cu collisions at RHIC-PHENIX

This paper discusses the production of J/y particles in collisions involving gold and copper ions at RHIC-PHENIX. The study focuses on the physics motivations, experimental setups, recorded data sets, model competition, and the observed suppression and effects on J/y production.

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J/ y production in Au+Au and Cu+Cu collisions at RHIC-PHENIX

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  1. J/y production in Au+Au and Cu+Cu collisions at RHIC-PHENIX Susumu Oda CNS, University of Tokyo For the PHENIX collaboration INPC2007, Tokyo, June 4, 2007, C1-5 1/10

  2. J/y c c-bar c low x Physics motivation • J/y is one of the most important probes for quark gluon plasma study. • J/y will dissociate in QGP by Debye screening. • Heavy quarks are created in initial hard collisions. • Mainly gluon fusion at RHIC energy • Competing effects • Cold nuclear matter effects • Nuclear absorption, shadowing, CGC • Feed down from y’, cc and bottom • Sequential dissociation • Regeneration from uncorrelated charm • Need to experimentally disentangle these effects. 2/10 C1-5 Oda

  3. Mid rapidity (|y|<0.35, e+e- pair) • Tracking • DC, MWPC • PID • RICH, EMCal Experimental setup • Forward rapidity (1.2<|y|<2.2, m+m- pair) • Tracking • MWPC • PID • Drift tube, absorber • Vertex, centrality • Timing, charged particle multiplicity • BBC • Spectator neutron • ZDC 3/10 C1-5 Oda

  4. Recorded data set To resolve the complications, collide several ion species with several energies. 4/10 C1-5 Oda

  5. Run-3 d+Au mm Mass plots Run-2 Au+Au ee Run-2 p+p mm Run-2 p+p ee Run-3 d+Au ee Run-3 p+p mm Run-3 p+p ee Run-4 Au+Au ee Run-4 Au+Au mm Run-5 p+p ee Run-5 p+p mm Run-5 Cu+Cu mm Run-5 Cu+Cu ee J/y mass : 3.097 GeV/c2 J/ye+e- : BR 5.94 +/- 0.06 % J/ym+m- : BR 5.93 +/- 0.06 % We have measured ~30k J/y by Run-5. 5/10 C1-5 Oda

  6. Npart and Ncoll are calculated by Glauber Monte Carlo. M.L. Miller et al., nucl-ex/0701025 Result RAA-Npart 0 mb R. VogtActa Phys. Hung. A25 (2006) 97 0 mb 3 mb 3 mb Red: Au+Au |y|<0.35 Magenta: Cu+Cu |y|<0.35 Blue: Au+Au 1.2<|y|<2.2 Aqua: Cu+Cu 1.2<|y|<2.2 deuteron gold Weak absorption and weak shadowing peripheral central • Suppression beyond cold nuclear matter effects. • Stronger suppression at forward rapidity than at mid rapidity for Npart>100. 6/10 C1-5 Oda

  7. Model competition Au+Au mid rapidity data Good agreement! Data and models at SPS Phys. Rev. C 69, 054903 (2004). • Orange solid: HSD, E.L.Bratkovskaya et al., PRC 71, 044901 (2005). • Blue: co-mover, A.Capella and E.G.Ferreiro hep-ph/0610313. • Orange dashed: SCM, A.Andronic et al., nucl-th/0701079. • Magenta: recombination, L.Grandchamp et al., PRL 92, 212301 (2004). • None reproduce RHIC data both at mid and forward rapidity well. • Relatively large errors in data at RHIC. • Relatively large variations in model predictions for RHIC. 7/10 C1-5 Oda

  8. RAA-rapidity • Flat RAA for Npart<100. • Rapidity narrowing in central Au+Au collisions • (Modest) Recombination? • NrecJ/ya Nc2 • Color Glass Condensate? • Measurement of J/y elliptic flow can make clear the origin of rapidity narrowing. Au+Au data CNM 0mb 3mb Full recombination SCM Open charm yield in A+A K.L. Tuchin J.Phys. G30 (2004) 1167 CGC =0 CNM : R. VogtActa Phys. Hung. A25 (2006) 97. SCM : A.Andronic et al., nucl-th/0701079. Full recombination : R.L.Thews and M.L.Mangano, PRC73 (2006) 014904. =2 8/10 C1-5 Oda

  9. RAA-pT and Ncoll-<pT2> Au+Au data • Magenta : R.L.Thews and M.L.Mangano, PRC73 (2006) 014904 and private comm. • Green : L.Yan, P.Zhuang and N.Xu, PRL97 (2006) 232301. • No strong pT dependence of RAA. • No significant centrality dependence of <pT2>. • RAA-pT has much more information than <pT2>. • I would like to see RAA-pT of model predictions. 9/10 C1-5 Oda

  10. Summary and outlook Expected resolution of J/y v2 with 2007 data • J/y is a nice tool for QGP study. • Strong suppression in Au+Au and Cu+Cu collisions beyond cold nuclear matter effects is observed. • Stronger suppression at forward rapidity than at mid rapidity in Au+Au central collisions • Moderate rapidity narrowing • No significant pT dependence of RAA • Cu+Cu final results will come soon. • Near future measurements • J/y elliptic flow (Run-7?) • New d+Au run will constrain CNM effects (Run-8?) • Feed down from ccm+m-g(NCC) and bJ/y (VTX) (Run-10?) • New detectors • Nose cone calorimeter • Silicon vertex detector 10/10 C1-5 Oda

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