Neutrino oscillations in the early universe. Resonant case Original Research Article

Lepton asymmetry generated in the early universe by neutrino oscillations into sterile partners is calculated. Kinetic equations are analytically reduced to a simple form that permits an easy numerical treatment. Asymptotic values of the asymmetry are at the level of 0.2–0.3 and are reasonably close to those obtained by other groups, though the approach to asymptotics in some cases is noticeably slower. No chaoticity is observed.