Nuclear absorption and J/ψ suppression in Pb plus Pb collisions -: art. no. 021902

We have analyzed the NA58 data on J/psi suppression in Pb+Pb collisions. J/psi production is assumed to be a two step process, (i) formation of c (c) over bar pair, which is accurately calculable in QCD and (ii) formation of J/psi meson from the c (c) over bar pair, which can be conveniently parametrized. In a pA/AA collision, a c (c) over bar pair gains relative square momentum as it passes through the nuclear medium and some of the c (c) over bar pairs can gain enough momentum to cross the threshold to become an open charm meson, leading to suppression in pA/AA collisions. A new prescription is proposed for the gain in momentum square, consistent with Krammer process. The model could explain the E-T dependence of J/psi over Drell-Yan ratio.