$J/\psi$ polarization in pp collisions at $\sqrt{s}$ = 7 TeV with the ALICE muon spectrometer at the LHC

In this thesis, the polarization measurement of J/psi inclusively produced in pp collisions at a center of mass energy of 7 TeV is presented. The analysis has been performed on data collected by the ALICE forward muon spectrometer during 2010 and it is based on the extraction of the angular distribution of the muons coming from the J/psi decay. The results obtained with this study represent the first measurement of quarkonia polarization at the LHC and they offer the possibility to test the theoretical models in a more than three times higher energy regime with respect to Tevatron. A first comparison with recent theoretical calculations is also presented in this document.