Quarkonium measurements via the di-muon decay channel in $\rm p$+$\rm p$ and $\rm Au$+$\rm Au$ collisions with the STAR experiment

TL;DR

This paper reports on the first measurements of $J/\psi$ and $\Upsilon$ quarkonia via di-muon decay at RHIC, revealing suppression patterns and model agreements in p+p and Au+Au collisions, with implications for quark-gluon plasma studies.

Contribution

It introduces the first $J/\psi$ and $\Upsilon$ measurements in the di-muon channel at RHIC using the new Muon Telescope Detector, providing new data on quarkonium suppression and regeneration.

Findings

$J/\psi$ cross section in p+p matches CGC+NRQCD and NLO NRQCD models.

Clear $J/\psi$ suppression observed in Au+Au collisions.

Hints of less melting of $\Upsilon(2S+3S)$ compared to $\Upsilon(1S)$ at RHIC.

Abstract

We present the first $J/\psi$ and $\Upsilon$ measurements in the di-muon decay channel at mid-rapidity at RHIC using the newly installed Muon Telescope Detector. In p$+$p collisions at $\sqrt{s}=500$~GeV, inclusive $J/\psi$ cross section can be described by CGC+NRQCD and NLO NRQCD model calculations for $0<p_T<20$~GeV/$c$. In Au$+$Au collisions at $\sqrt{s_{NN}}=200$~GeV, we observe (i) clear $J/\psi$ suppression indicating dissociation; (ii) $J/\psi$ $R_{AA}$ can be qualitatively described by transport models including dissociation and regeneration with a tension at high $p_T$; and (iii) hint of less melting of $\Upsilon(2S+3S)$ relative to $\Upsilon(1S)$ at RHIC compared to that at LHC.