Measurements of the transverse-momentum-dependent cross sections of $J/\ddot{I}ˆ$ 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 $J/\ddot{I}ˆ$ meson production as a function of transverse momentum ($p_T^{J/\ddot{I}ˆ}$) using the $\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ 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 $\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ channel is for 0 $<p_T^{J/\ddot{I}ˆ}<$ 9 GeV/$c$ and rapidity range $|y^{J/\ddot{I}ˆ}|<$ 0.4, and that from the $e^{+}{e}^{-}$ channel is for 4 $<p_T^{J/\ddot{I}ˆ}<$ 20 GeV/$c$ and $|y^{J/\ddot{I}ˆ}|<$ 1.0. The $\ddot{I}ˆ(2S)$ to $J/\ddot{I}ˆ$ ratio is also measured for 4 $<p_T^{\mathrm{meson}}<$ 12 GeV/$c$ through the $e^{+}{e}^{-}$ decay channel. Model calculations, which incorporate different approaches toward the $J/\ddot{I}ˆ$ production mechanism, are compared with experimental results and show reasonable agreement within uncertainties.