Quarkonium measurements in nucleus--nucleus collisions with ALICE

Abstract

Quarkonia, i.e. bound states of $b\bar{b}$ and $c\bar{c}$ quarks, are powerful observables to study the properties of nuclear matter under extreme conditions. The formation of a Quark-Gluon Plasma (QGP), which is predicted by lattice QCD calculations at high temperatures as reached at LHC energies, has a strong influence on the production and behavior of quarkonia. The latest ALICE results on bottomonium and charmonium production in nucleus$-$nucleus collisions are presented. This includes measurements of the $\Upsilon$(1S) and $\Upsilon$(2S) nuclear modification factors ($R_{\mathrm{AA}}$) at forward rapidity and the J/$\psi$ $R_{\mathrm{AA}}$ and $v_{2}$ as a function of centrality, $p_{\mathrm T}$ and rapidity in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. Also, first results from J/$\psi$ measurements in Xe$-$Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV are presented. Further on, the experimental results are compared to various calculations from theoretical models.