The Lepton Asymmetry of the Universe

The standard hot big bang cosmological model has been extremely successful in explaining the Tγ ≃ 2.7 °K microwave radiation and the relative abundance of primordial helium and deuterium [1]. When combined with the ideas of grand unification [2] it may also give a plausible dynamical explanation of the small baryon asymmetry B ≡ (nB −n B − )/nγ ≃ 10−10±1 observed in the present universe.