Quarkonium measurements in heavy-ion collisions at $\sqrt{s_{\text{NN}}}$ = 200 GeV with the STAR experiment

Abstract

We present the latest J/$\psi$ and $\Upsilon$ measurements in p+p, p+Au and Au+Au collisions at ${\sqrt{s_{_{\rm NN}}}} = 200\;{\rm GeV}$ by the STAR experiment. In p+p collisions, the inclusive $\Upsilon$ cross section is measured through the di-electron decay channel, while the inclusive J/$\psi$ polarization parameters are obtained from both the di-muon and di-electron channels. The later are compared to the Non-Relativistic QCD (NRQCD) models. In p+Au collisions, the measured nuclear modification factor for J/$\psi$ suggests additional suppression mechanism besides the nuclear PDF (nPDF) effect. The latest $\Upsilon$ measurements in Au+Au collisions reach a higher precision by combining the data sets taken in 2011, 2014 and 2016, compared to previous results. The nuclear modification factors for the ground and excited $\Upsilon$ states in Au+Au collisions are shown as a function of the number of participants, and compared to the results at the LHC as well as to theoretical calculations.