$J/\psi$ production in Au+Au collisions at RHIC and the nuclear absorption

Abstract

It is shown that a QCD based nuclear absorption model, with few parameters fixed to reproduce experimental $J/\psi$ yield in 200 GeV pp/pA and 450 GeV pA collisions can explain the preliminary PHENIX data on the centrality dependence of $J/\psi$ suppression in Cu+Cu collisions at RHIC energy, $\sqrt{s_{NN}}$=200 GeV. However, the model does not give satisfactory description to the preliminary PHENIX data on the centrality dependence of $J/\psi$ suppression in Au+Au collisions. The analysis suggest that in Au+Au collisions, $J/\psi$ are suppressed in a medium unlike the medium produced in SPS energy nuclear collisions or in RHIC energy Cu+Cu collisions.Comment: Revised version, published in Phys. Rev. C 74(2006)044907. PHENIX preliminary data on the centrality dependence of nuclear modification factor for $J/\psi$ in Cu+Cu and in Au+Au are analysed. 6 pages, 5 figure