(Non) thermal aspects of charmonium production and a new look at J/ψ suppression

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 cion-thermal origin of hidden charm production at SPS energy. However, the ratio psi'/(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 he discussed. (C) 2000 Elsevier Science B.V. All rights reserved.