Formula omitted] production in p-A and A-A collisions at fixed target experiments

Abstract

Charmonia suppression is one of the main signatures for the formation of a deconfined medium. However, also nuclear effects, not related to the production of a hot medium, can affect the J / ψ yield. The determination, from the study of p-A collisions, of the J / ψ behaviour in nuclear matter is, therefore, extremely important to correctly quantify the amount of charmonia suppression induced by the deconfined medium. In this paper the new NA60 results collected at 158 GeV incident energy, i.e. under the same kinematical conditions as the In-In (NA60) and Pb-Pb (NA50) data, are presented and compared with p-A measurements from other fixed target experiments. rESULTS on A-A collisions are also reviewed taking into account the new available information on the influence of cold nuclear matter on the J / ψ production yield. Finally, results on the J / ψ polarization are shown for p-A and A-A collisions.