Centrality, rapidity and transverse momentum dependence of J/ψ suppression in Pb–Pb collisions at sNN = 2.76 TeV

Abstract

he inclusive J/ψ nuclear modification factor (RAA) in Pb–Pb collisions at √sNN = 2.76 TeV has been measured by ALICE as a function of centrality in the e+e− decay channel at mid-rapidity (|y| < 0.8) and as a function of centrality, transverse momentum and rapidity in the μ+μ− decay channel at forward-rapidity (2.5 < y < 4). The J/ψ yields measured in Pb–Pb are suppressed compared to those in pp collisions scaled by the number of binary collisions. The RAA integrated over a centrality range corresponding to 90% of the inelastic Pb–Pb cross section is 0.72 ± 0.06(stat.) ± 0.10(syst.) at mid-rapidity and 0.58 ± 0.01(stat.) ± 0.09(syst.) at forward-rapidity. At low transverse momentum, significantly larger values of RAA are measured at forward-rapidity compared to measurements at lower energy. These features suggest that a contribution to the J/ψ yield originates from charm quark (re)combination in the deconfined partonic medium.