J/ψ production in Pb-Pb collisions at =2.76 TeV in the ALICE experiment

Abstract

Quarkonium states are expected to provide essential information on the properties of the high-density strongly-interacting system formed in the early stages of heavy-ion collisions. In particular the J/ψ suppression via color screening is a direct consequence of deconfinement. ALICE is the LHC experiment specifically designed to study nucleus-nucleus collisions. The production of heavy quarkonium states is measured by ALICE down to zero transverse momentum via the μ+μ− decay channel in the Forward Muon Spectrometer (2.5 < y < 4) and via the e+e− decay channel in the central barrel at mid rapidity (|y| < 0.9). The analysis of the inclusive J/ψ production in Pb-Pb collisions at a center of mass energy per nucleon pair =2.76 TeV is presented. The inclusive J/ψ nuclear modification factor as a function of centrality, transverse momentum and rapidity is shown and compared to similar measurements by other experiments and to theoretical predictions. Finally, a hint of a low transverse momentum J/ψ yield excess, with respect to the expected hadronic channel production, is discussed.