# 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

## TL;DR

This paper reports measurements of the differential cross sections of $J/$ meson production in proton-proton collisions at 510 and 500 GeV, using the STAR detector, and compares results with theoretical models.

## Contribution

It provides new differential cross section data for $J/$ production at these energies and rapidities, and compares them with various theoretical models.

## Key findings

- Reasonable agreement between data and models within uncertainties.
- Measured $J/$ cross sections over a broad $p_T$ range.
- First measurements of $$ to $J/$ ratio at these energies.

## 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.