Measurement of jpsi production in p+p collisions at \sqrts = 500 GeV at STAR experiment

Abstract: 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 jpsi with transverse momentum (pT) above 4 GeV/c at mid-rapidity in p+p collisions at \sqrts = 500 GeV by the STAR experiment. The ratio of the yield of psi(2S) to jpsi integrated over 4 < pT < 12 GeV/c is also presented. Furthermore, the jpsi yields are studied in different event multiplicity bins in different jpsi pT regions, where the low pT measurement is enabled by the newly installed Muon Telescope Detector. A strong increase of the relative jpsi yield with the event multiplicity is observed for all pT with significant pT dependence.