• cms
• lhc
• polarization
• vector

In this thesis, the theoretical SM predictions for vector boson polarization are first presented, and the mechanism leading to this effect discussed; then, after having introduced the properties of physics objects used in the analysis, the first measurement of W and Z polarization at a proton-proton collider with the Compact Muon Solenoid (CMS) is reported. Polarization information is extracted in the helicity frame from distributions of kinematic quantities of decay leptons by means of a fit with templates obtained by a MC simulation. Results are compared to expectations from theoretical Standard Model calculations. They are found to be consistent with each other within the present sensitivity.