Measurement of cold nuclear matter effects for inclusive $J/\psi$ in $p$+Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV

The STAR collaboration Abdallah, Mohamed ; Aboona, Bassam ; Adam, Jaroslav ; et al.
Phys.Lett.B 825 (2022) 136865, 2022.
Inspire Record 1946829 DOI 10.17182/hepdata.114371

Measurement by the STAR experiment at RHIC of the cold nuclear matter (CNM) effects experienced by inclusive $J/\psi$ at mid-rapidity in 0-100%$p$+Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV is presented. Such effects are quantified utilizing the nuclear modification factor, $R_{p\mathrm{Au}}$, obtained by taking a ratio of $J/\psi$ yield in $p$+Au collisions to that in $p$+$p$ collisions scaled by the number of binary nucleon-nucleon collisions. The differential $J/\psi$ yield in both $p$+$p$ and $p$+Au collisions is measured through the dimuon decay channel, taking advantage of the trigger capability provided by the Muon Telescope Detector in the RHIC 2015 run. Consequently, the $J/\psi$$R_{p\mathrm{Au}}$ is derived within the transverse momentum ($p_{\mathrm{T}}$) range of 0 to 10 GeV/$c$. A suppression of approximately 30% is observed for $p_{\mathrm{T}}<2$ GeV/$c$, while $J/\psi$ $R_{p\mathrm{Au}}$ becomes compatible with unity for $p_{\mathrm{T}}$ greater than 3 GeV/$c$, indicating the $J/\psi$ yield is minimally affected by the CNM effects at high $p_{\mathrm{T}}$. Comparison to a similar measurement from 0-20% central Au+Au collisions reveals that the observed strong $J/\psi$ suppression above 3 Gev/$c$ is mostly due to the hot medium effects, providing strong evidence for the formation of the quark-gluon plasma in these collisions. Several model calculations show qualitative agreement with the measured $J/\psi$ $R_{p\mathrm{Au}}$, while their agreement with the $J/\psi$ yields in $p$+$p$ and $p$+Au collisions is worse.

3 data tables

Inclusive J/psi cross section times branching ratio of the dimuon decay channel in p+p collisions at 200 GeV. Global uncertainty of 12.5% not shown.

Inclusive J/psi cross section times branching ratio of the dimuon decay channel in p+Au collisions at 200 GeV. Global uncertainty of 1.5% not shown.

R_pAu of inclusive J/psi in p+Au collisions at 200 GeV. Global uncertainty of 13.9% not shown.