Neutrino Masses in Cosmology

The determination of neutrino masses is one of the main challenge in physics today. From the particle physics point of view the main techniques to infer bound over the absolute neutrino mass scales are beta and (neutrinoless) beta decay. However, cosmological observations such as CMB and LSS can be used to infer constraint on the sum of the neutrino masses, which are even tighter. The aim of this thesis is to review, from a theoretical prospective, how massive neutrinos can be included in the cosmic history both at background and perturbation level (through free streaming) and the direct consequences on the matter distribution at large scales and CMB. A briefly description of the main experimental methods used for measuring the LSS and CMB power spectrum is also reported, together with present results from CMB or LSS data alone and joint analysis.