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

Abstract

The inclusive J/ψJ/ψ nuclear modification factor (RAARAA) in Pb–Pb collisions at sNN=2.76 TeV has been measured by ALICE as a function of centrality in the e+e−e+e− decay channel at mid-rapidity (

y

<0.8

y

<0.8) and as a function of centrality, transverse momentum and rapidity in the μ+μ−μ+μ− decay channel at forward-rapidity (2.5<y<42.5<y<4). The J/ψJ/ψ yields measured in Pb–Pb are suppressed compared to those in pp collisions scaled by the number of binary collisions. The RAARAA integrated over a centrality range corresponding to 90% of the inelastic Pb–Pb cross section is 0.72±0.06(stat.)±0.10(syst.)0.72±0.06(stat.)±0.10(syst.) at mid-rapidity and 0.58±0.01(stat.)±0.09(syst.)0.58±0.01(stat.)±0.09(syst.) at forward-rapidity. At low transverse momentum, significantly larger values of RAARAA are measured at forward-rapidity compared to measurements at lower energy. These features suggest that a contribution to the J/ψJ/ψ yield originates from charm quark (re)combination in the deconfined partonic medium.