J/ψ production in indium-indium collisions

The study of dilepton production in heavy-ion collisions at the CERN SPS provided some of the most interesting observations done so far in the search for the quark gluon plasma. However, several aspects of the understanding of these measurements need to be clarified. For example, the study of the J/ψ production in different colliding systems should help to disentangle which is the variable driving the J/ψ suppression. The NA60 experiment, with a new radiation tolerant Silicon pixel detector, studied Indium-Indium interactions in the year 2003. In this paper, we present the J/ψ/DY ratio, integrated over all the centralities of the collisions, together with a first study of the J/ψ transverse momentum and polarization. (orig.)