Étude de la production inclusive de $J/\psi$ dans les collisions Pb-Pb à $\sqrt{s_{_{\rm NN}}}=2,76$ TeV avec le spectromètre à muons de l'expérience ALICE au LHC

The quantum chromodynamics theory predicts the existence of a deconfined state of matter called Quark Gluon Plasma (QGP). Experimentally, the formation of a QGP is expected under the extreme conditions of temperature and density reached in ultra-relativistic heavy-ion collisions. Many observables were proposed to observe and characterize indirectly such a state of matter. In particular, the phenomena of suppression and (re)combination of the $J/\psi$ meson in the QGP are extensively studied. This thesis presents the analysis of the inclusive production of $J/\psi$ in Pb-Pb collisions, at a center of mass energy $\sqrt{s_{_{\rm NN}}}=2.76$ TeV, detected with the ALICE muon spectrometer at the LHC. From the high statistics of events collected during 2011 data taking, the $J/\psi$ nuclear modification factor was measured as a function of transverse momentum, rapidity and collision centrality. The $J/\psi$ mean transverse momentum was also measured as a function of centrality. The predictions of theoretical models, all including a (re)combination contribution, are in good agreement with data. Finally, an excess of $J/\psi$ yield at very low transverse momentum (<300 MeV/$c$) with respect to the expected hadronic production was observed for the first time.