Measurement of J/ps production in p p collisions at s=500 GeV at STAR experiment
Quarkonium measurements in heavy ion collisions play an essential role in understanding the hot, dense medium created in such collisions. As a reference, their production mechanism in p p collisions needs to be thoroughly understood. In this paper, we report the measurement of inclusive cross section of J/ps with transverse momentum (pT) above 4 GeV/c at mid rapidity in p p collisions at s=500 GeV by the STAR experiment. The ratio of the yield of ps(2S) to J/ps integrated over 4<pT<12 GeV/c is also presented. Furthermore, the J/ps yields are studied in different event multiplicity bins in different J/ps pT regions, where the low pT measurement is enabled by the newly installed Muon Telescope Detector. A strong increase of the relative J/ps yield with the event multiplicity is observed for all pT with significant pT dependence.