Quarkonium formation time in relativistic heavy-ion collisions

We have studied the quarkonium formation time in relativistic heavy-ion collisions from the space-time correlator of heavy quark vector currents in a hydrodynamics background. Using in-medium quarkonia properties determined with the heavy quark potential taken to be the free energy from lattice calculations and taking into account the fact that quarkonia can only be formed below their dissociation temperatures due to color screening, we have found that the formation time of a quarkonium is significantly increased in a medium, compared to its value in the vacuum. We have further found that including the effect of formation time enhances appreciably the survivability of a quarkonium in the hot dense matter produced in a heavy ion collision. Relevance of our results to the understanding of quarkonium production in relativistic heavy ion collisions is briefly discussed.