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

To investigate a recent proposal that J/psi production in ultra-relativisti c nuclear collisions is of thermal origin we have reanalyzed the data from the NA38/50 Collaboration within a thermal model including charm. Compariso n of the calculated with measured yields demonstrates the cion-thermal orig in of hidden charm production at SPS energy. However, the ratio psi'/(J/psi ) exhibits, in central nucleus-nucleus collisions, thermal features which l ead us to a new interpretation of open charm and charmonium production at S PS energy. Implications for RHIC and LHC energy measurements will he discus sed. (C) 2000 Elsevier Science B.V. All rights reserved.