Cosmological measurement of neutrino mass in the presence of leptonic asymmetry

Abstract We review some cosmological consequences of a relic lepton asymmetry in the form of neutrinos. A relic neutrino degeneracy enhances the contribution of massive neutrinos to the present energy density of the Universe, and modifies the power spectrum of radiation and matter. In particular we show that even the smallest neutrino mass consistent with the Super-Kamiokande data is relevant for cosmological models of structure formation and cosmic microwave background (CMB) anisotropies, provided that a relic neutrino asymmetry exists.