Charmonium production from the hadronic phase

Charmonium production from the hadron gas formed in ultra-relativistic heavy-ion collisions is studied. Using the J/ψ-hadron absorption cross section determined from the nonperturbative quark-exchange model, which has a peak value similar to that used in the comover model for J/ψ suppression and a thermally averaged value consistent from that extracted from J/ψ data in heavy-ion collisions, we find that J/ψ production from the hadron gas is negligible in heavy-ion collisions at RHIC energies but is important at LHC energies as a result of the large number of charm mesons produced at higher energy collisions. The number of J/ψ produced from these secondary collisions at LHC may be comparable to that of primary J/ψ’s, which are expected to be dissociated in the quark-gluon plasma created in the collisions, leading thus to a possible absence of J/ψ suppression. Similar results are obtained for ψ production in ultra-relativistic heavy-ion collisions. PACS: 25.75.-q, 24.10.Lx