J/ψ Suppression in an Equilibrating Parton Plasma

Short-distance QCD is employed to calculate the J/ψ survival probability in an equilibrating parton gas, whose evolution is governed by a set of master rate equations. Partons in the early stage of high-energy nuclear collisions may initially not be in equilibrium, but their average transverse momentum is sufficiently high to break up a QQ̄ bound state. Such a break-up during the evolution of the parton gas is shown to cause a substantial J/ψ suppression at both RHIC and LHC energies, using realistic estimates of the initial parton densities. The transverse momentum dependence of the suppression is also shown to be sensitive to the initial conditions and the evolution history of the parton plasma.