Measurements of the transverse-momentum-dependent cross sections of $J/\psi$ production at mid-rapidity in proton+proton collisions at $\sqrt{s}$ =510 and 500 GeV with the STAR detector

Abstract

We present measurements of the differential cross sections of inclusive $J/\psi$ meson production as a function of transverse momentum ($p_{T}^{J/\psi}$) using the $\mu^{+}\mu^{-}$ and $e^+e^−$ decay channels in proton+proton collisions at center-of-mass energies of 510 and 500 GeV, respectively, recorded by the STAR detector at the Relativistic Heavy Ion Collider. The measurement from the $\mu^{+}\mu^{-}$ channel is for 0 < $p_{T}^{J/\psi}$ < 9 GeV/$c$ and rapidity range $|y^{J/\psi}|$ < 0.4, and that from the $e^+e^−$ channel is for 4 < $p_{T}^{J/\psi}$ < 20 GeV/$c$ and $|y^{J/\psi}|$ < 1.0. The $\psi(2S)$ to $J/\psi$ ratio is also measured for 4 < $p_{T}^{\rm meson}$ < 12 GeV/$c$ through the $e^+e^−$ decay channel. Model calculations, which incorporate different approaches toward the $J/\psi$ production mechanism, are compared with experimental results and show reasonable agreement within uncertainties.