Quark Matter 2005 Conference   Quark Matter 2005 Conference

Anomalous J/psi suppression in Indium-Indium collisions at 158 GeV/nucleon

Dr. Roberta Arnaldi

Collaboration: NA60


The NA60 experiment collected data on dimuon production in In-In collisions at 158 GeV per incident nucleon. In this talk, we address the centrality dependence of J/psi production, by comparing the J/psi/Drell-Yan ratio with the results previously obtained by NA38/NA50 in S-U and Pb-Pb collisions. We will show that indeed an anomalous J/psi suppression is present in In-In collisions and we will investigate the suppression pattern as a function of several centrality variables, as L, Npart and the energy density, in order to identify possible scaling behaviours, related to different physics mechanisms driving the suppression. To increase the statistical significance of our study, reference processes alternative to Drell-Yan are being considered and preliminary results in this sense will be shown. We will also show p-A data collected in 2004, with 158 GeV protons, to determine the normal nuclear absorption of the J/psi in the energy and kinematical domains of the heavy-ion data.

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