Can $J/\psi$ suppression and $p_T$ broadening signal the deconfinement transition at RHIC?

Abstract

We have analyzed the latest NA50 data on $J/\psi$ suppression in Pb+Pb collisions at CERN SPS. It is shown that a QCD based nuclear absorption model, where $J/\psi$'s are absorbed in nuclear medium could explain the latest NA50 data on the centrality dependence of the $J/\psi$ over Drell-Yan ratio. The model also explains the NA50 data on $J/\psi$ over minimum bias ratio and the $p_T$ broadening of $J/\psi$'s. A QGP based threshold model where all the $J/\psi$'s are suppressed above a threshold density, also explains the data sets with smeared threshold density. Even at RHIC energy, centrality dependence of $J/\psi$ suppression or $p_T$ broadening could not distinguish between the two models.

Comments: 8 pages, 8 figures. In the revised version, latest NA50 data (2000 run) on the centrality dependence of $J/\psi$ over Drell-Yan ratio are analysed in the QCD based nuclear absorption model and in the QGP based threshold model. In addition NA50 data on the centrality dependence of $J/\psi$ over minimum bias ratio and $p_T$ broadening of $J/\psi$'s are analysed. Prediction for RHIC Au+Au collisions are given