Charmonia and Drell-Yan production in proton-nucleus collisions at the CERN SPS

Charmonium production in p-A collisions is a unique tool for the study of the interaction of bound cc-bar states in nuclear matter. It can provide details on the basic features of the resonance formation mechanism and, in particular, on its non-perturbative aspects. In this Letter, we present an experimental study of charmonia and Drell-Yan production in proton-nucleus collisions at 450 GeV/c. The results are analyzed in the framework of the Glauber model and lead to the values of the nuclear absorption cross-section σabspA for J/ψ and ψ'. Then, we compare the J/ψ absorption in proton-nucleus and sulphur-uranium interactions, using NA38 data. We obtain that, for the J/ψ, σabspA and σabsSU are compatible, showing that no sizeable additional suppression mechanism is present in S-U collisions, and confirming that the anomalous J/ψ suppression only sets in for Pb-Pb interactions