CHARMONIUM SUPPRESSION IN HEAVY-ION COLLISIONS

Data and their interpretations are reviewed for J/ψ and ψ′ production in heavy-ion collisions with particular emphasis on the recently reported anomaly in Pb-Pb reactions. The observed suppressions in pA collisions are discussed in terms of final-state absorption of a pre-meson and the pT distributions due to parton scattering in the initial state. The experimental setup is described and the various results for J/ψ and ψ′ suppressions, including their pT-dependence, are presented. The data, in particular the observed anomalous suppression in Pb-Pb collisions, are discussed in the light of the proposed ideas, among them quark-gluon plasma formation and suppression via co-movers.