J/ψ production in In–In and p–A collisions

Abstract

The NA60 experiment studies dimuon production in In–In and p–A collisions at the CERN SPS. We report recent results on J/ψ production, measured through its muon pair decay. As a function of centrality, we show that in In–In the J/ψ yield is suppressed beyond expectations from nuclear absorption. We present also for the first time results on J/ψ production in p–A collisions at 158 GeV, the same energy of the nucleus–nucleus data. For both p–A and In–In we show preliminary results on ψ′ suppression. Finally, we have studied the kinematical distributions of the J/ψ produced in In–In collisions. We present results on transverse momentum and rapidity, as well as on the angular distribution of the J/ψ decay products.