Measurement of inclusive $J/\ddot{I}ˆ$ suppression in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV through the dimuon channel at STAR

Abstract

$J/\ddot{I}ˆ$ suppression has long been considered a sensitive signature of the formation of the Quark-Gluon Plasma (QGP) in relativistic heavy-ion collisions. In this letter, we present the first measurement of inclusive $J/\ddot{I}ˆ$ production at mid-rapidity through the dimuon decay channel in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV with the STAR experiment. These measurements became possible after the installation of the Muon Telescope Detector was completed in 2014. The $J/\ddot{I}ˆ$ yields are measured in a wide transverse momentum ($p_{\mathrm{T}}$) range of 0.15 GeV/$c$ to 12 GeV/$c$ from central to peripheral collisions. They extend the kinematic reach of previous measurements at RHIC with improved precision. In the 0-10% most central collisions, the $J/\ddot{I}ˆ$ yield is suppressed by a factor of approximately 3 for $p_{\mathrm{T}}>5$ GeV/$c$ relative to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The $J/\ddot{I}ˆ$ nuclear modification factor displays little dependence on $p_{\mathrm{T}}$ in all centrality bins. Model calculations can qualitatively describe the data, providing further evidence for the color-screening effect experienced by $J/\ddot{I}ˆ$ mesons in the QGP.