If Quarkonia Could Talk: From SPS to RHIC

Quarkonia provide a direct probe of hard parton interactions that occur in nucleon-nucleon collisions. Because the heavy quark pairs interact with the medium produced in heavy ion collisions, information regarding the properties of the collision environment is accessible through the quarkonia that escape. Quarkonia are useful probes of the collision medium because they are sensitive to the modification of the QCD confining potential. Measurements of quarkonia produced in p + p, p + A and d + A collision systems provide reference information necessary for understanding their production mechanisms and for disentangling cold nuclear matter effects present in heavy ion data. Studies of heavy ion collisions can be used to quantify in medium modifications. Experimental results from both the SPS and RHIC are presented in the context of the available theoretical interpretations (author)