Quarkonia as probes of the QGP and of the initial stages of the heavy-ion collision with ALICE

Abstract

Studies of quarkonium production in heavy-ion collisions can be used for probing QGP properties. The suppression and regeneration of bound quarkonium states is sensitive to the medium properties. Modifications of the quarkonium polarization in Pb–Pb collisions with respect to pp collisions may give further insight into the suppression and regeneration mechanisms in the QGP. Quarkonia are also sensitive to the initial stages of heavy-ion collisions, and measurements in photonuclear collisions may help constrain the nuclear gluon-distribution at low Bjorken-x. In this work, recent quarkonium measurements performed by ALICE in Pb–Pb collisions at √SNN = 5.02 TeV will be discussed. Preliminary measurements of the inclusive J/ψ RAA measured at both forward and central rapidity will be presented. The J/ψ polarization measured for the first time in Pb–Pb collisions, as well as preliminary measurements of the coherent J/ψ photoproduction cross section, will be discussed.