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

Abstract

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