J/ψ production in proton+proton and heavy-ion collisions at STAR

Measurements of J/ψ production in proton+proton and Au+Au collisions using the STAR detector are presented. The differential cross-sections measured through both the dielectron and dimuon channels in proton+proton collisions at s=200 and 500 GeV have reasonable agreement with CEM, CGC+NRQCD and NLO NRQCD predictions in kinematic ranges in which these models are applicable. Additionally, the ratio of production cross-section times the dielectron branching fraction of ψ(2S) to J/ψ is consistent with other experiments and the relative J/ψ yield as a function of the relative charged-particle multiplicity can be qualitatively described by theoretical predictions. In Au+Au collisions at s_NN=200 GeV, the nuclear modification factor (R_AA) compared with transport models and J/ψ elliptic flow (v₂) as a function of transverse momentum are also discussed.