Quarkonium production in ALICE at the LHC

Abstract: In heavy-ion collisions at the LHC, the ALICE Collaboration is studying Quantum Chromodynamics (QCD) matter at very high energy density where the formation of a Quark Gluon Plasma (QGP) is expected. Quarkonium production is an important probe to characterize the QGP properties. High precision data in pp collisions provide the baseline of Pb-Pb measurements and p-Pb collisions serve to quantify the amount of initial and/or final state effects, related to cold nuclear matter, that are largely unknown at the LHC energy. Since 2010, the LHC provided Pb-Pb collisions at sqrt{s_{NN}} = 2.76 TeV, pp collisions at various energies and in 2013 p-Pb collisions at sqrt{s_{NN}} = 5.02 TeV. In ALICE, quarkonia can be reconstructed at forward rapidity in the dimuon channel and at mid-rapidity in the dielectron channel, and, for both channels, down to zero transverse momentum. New measurements on inclusive production of J/psi, psi (2S) and Upsilon performed in p-Pb collisions and on the p_T dependence of inclusive J/psi in Pb-Pb collisions are presented. The contribution of J/psi from B hadrons to the inclusive production in Pb-Pb is also discussed. Finally, an estimation of the cold nuclear matter effect in Pb-Pb, extrapolated from p-Pb measurements, is given.