Transverse momentum and transverse mass distributions of mesons produced in p-A and PbPb interactions at the CERN SPS

Abstract We present a study of the transverse momentum and transverse mass of J ψ mesons produced in nucleus-nucleus and p-nucleus reactions. They include the most recent data collected by the NA50 experiment in PbPb and p-A reactions at 158 GeV/c and 400 GeV/c incident momentum respectively. Together with S-U results previously published by experiment NA38, the mean squared transverse momentum of J ψ mesons exhibit a scaling behaviour which could result from initial state parton interaction. However, for the most central PbPb collisions a saturation effect is observed as a function of centrality.