ϒ production in p+p, d+Au, Au+Au collisions at [formula omitted] in STAR

Abstract

Quarkonium is a good probe of the dense matter produced in heavy-ion collisions at RHIC because it is produced early in the collision and the production is theorized to be suppressed due to the Debye color screening of the potential between the heavy quarks. A model dependent measurement of the temperature of the Quark Gluon Plasma (QGP) can be made by examining the ratio of the production of various quarkonium states in heavy ion collisions versus p+p collisions as lattice calculations indicate that the quarkonium states will be sequentially suppressed. Suppression is quantified by calculating R A A , which is the ratio of the yield in Au+Au to the production in p+p scaled by the number of binary collisions. The ϒ states are of particular interest because at 200 GeV the effects of feed down and co-movers are smaller than for J / ψ which decreases the systematic uncertainty of the R A A determination. In addition to hadronic absorption, additional cold nuclear matter effects, such as shadowing of the PDFs, can be determined from d+Au collisions. We will present our results for mid-rapidity ϒ production in p+p, as well as our preliminary results in d+Au and Au+Au at s = 200 GeV . These results will then be compared with theoretical QCD calculations.