Sequential charmonium dissociation

Finite temperature lattice QCD indicates that the charmonium ground state J/ψ can survive in a quark-gluon plasma up to 1.5Tc or more, while the excited states χc and ψ′ are dissociated just above Tc. We assume that the χc suffers the same form of suppression as that observed for the ψ′ in SPS experiments, and that the directly produced J/ψ is unaffected at presently available energy densities. This provides a parameter-free description of J/ψ and ψ′ suppression which agrees quite well with that observed in SPS and RHIC data.