Quarkonia as probes of the QGP and the initial stages of the heavy-ion collisions 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 $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV will be discussed. Preliminary measurements of the inclusive J/$\psi$ $R_{\rm AA}$ measured at both forward and midrapidity will be presented. The J/$\psi$ polarization measured for the first time in Pb-Pb collisions, as well as preliminary measurements of the coherent J/$\psi$ photoproduction cross section, will be discussed.