(Non)Thermal Aspects of Charmonium Production and a New Look at J/$\psi$ Suppression

Abstract

To investigate a recent proposal that J/$\psi$ production in ultra-relativistic nuclear collisions is of thermal origin we have reanalyzed the data from the NA38/50 collaboration within a thermal model including charm. Comparison of the calculated with measured yields demonstrates the non-thermal origin of hidden charm production at SPS energy. However, the ratio ${\psi }^{{}^{\prime }}$/(J/$\psi )$ exhibits, in central nucleus-nucleus collisions, thermal features which lead us to a new interpretation of open charm and charmonium production at SPS energy. Implications for RHIC and LHC energy measurements will be discussed.

Comments: 12 pages, 3 eps figures, final version with slight corrections, Phys. Lett. B (in print)