Measurement of ϒ production in p+p collisions at = 500 GeV in the STAR experiment

Abstract

Quarkonium suppression was proposed as a signature of the quark-gluon plasma (QGP) formation. Different members of the quarkonium family are expected to melt at different temperatures providing an estimate of the temperature reached in the QGP. The ϒ states offer a clean probe of the QGP, thanks to small secondary production and cold nuclear matter effects. Previous measurements at RHIC focused on colliding system and centrality dependence of ϒ nuclear modification factor RAA. The ϒ RAA as a function of pT will provide additional information about ϒ interaction with the QGP, which requires a pT spectrum in p+p collisions as a baseline. Measurement of the ϒ pT spectrum in p+p collisions at = 500 GeVmay provide such a baseline with high precision. It can be rescaled based on pQCD calculations and used as a baseline for Au+Au collisions at = 200 GeV.In this paper, the status of ϒ measurements in p+p collisions at = 500 GeVin the STAR experiment is presented. In addition, with the help of the newly installed Muon Telescope Detector (MTD) it will be possible to measure ϒ 1S, 2S and 3S states separately.