Recent Measurements of Heavy Quarkonium Production in Au+Au, p+Au and p+p Collisions at STAR

Abstract

Heavy quarkonia are useful probes of the quark-gluon plasma, where quarkonium dissociation is expected at high enough temperature. Indeed, such a suppression is clearly present in the latest STAR measurements of J/ψ production in Au+Au collisions. The suppression is observed to have little dependence on pT, although cold-nuclear matter (CNM) effects, such as shadowing, anti-shadowing and nuclear absorption can play a significant role at low pT. Measurements of the J/ψ production in p+A collisions can help us to disentangle the CNM effects from the hot medium effects in A+A collisions. In these proceedings, we will present the measurement of J/ψ production in p+Au collisions at sNN=200GeV by the STAR experiment. In addition, we will present recent STAR measurements of J/ψ and ϒ production in p+p collisions including their dependence on the charged-particle multiplicity at mid-rapidity. These measurements are important for understanding the mechanism of the heavy quarkonium production in elementary nucleon-nucleon collisions and the interplay of soft and hard processes.