PUB - Publikationen an der Universität Bielefeld

Quarkonium production has been considered as a tool to study the mediumformed in high energy nuclear collisions, assuming that the formation of a hotand dense environment modifies the production pattern observed in elementarycollisions. The basic features measured there are the relative fractions ofhidden to open heavy flavor and the relative fractions of the different hiddenheavy flavor states. Hence the essential question is if and how thesequantities are modified in nuclear collisions. We show how the relevant datamust be calibrated, i.e., what reference has to be used, in order to determinethis in a model-independent way.