Charmonium production from the hadronic phase

Abstract

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 $ψ^\prime$ production in ultra-relativistic heavy-ion collisions.