image Suppression in In-In Collisions at 158 GeV/n Original Research Article

The NA60 experiment has studied J/ψ production in Indium-Indium collisions at 158 A⋅GeV. In this paper we present an updated set of results obtained with the complete set of available statistics and an improved alignment of the vertex tracker. The centrality dependence of the J/ψ production, obtained with an analysis technique based only on the J/ψ sample, indicates that a suppression beyond that induced by nuclear absorption is present in In-In collisions, setting in at ∼80 participant nucleons. A first study of the systematic errors related with this measurement is discussed. We also present preliminary results on the J/ψ azimuthal distributions.