Neutrino masses from universal fermion mixing

If three right-handed neutrinos are added to the Standard Model, then, for the three known generations, there are six quarks and six leptons. It is then natural to assume that the symmetry considerations that have been applied to the quark matrices are also valid for the lepton mass matrices. Under this assumption, the solar and atmospheric neutrino data can be used to determine the individual neutrino masses. Using the � 2 fit, it is found that the mass of the lightest neutrino is (2‐5) × 10 −3 eV, that of the next heavier neutrino is (10‐13) × 10 −3 eV, while the mass of the heaviest neutrino is (52‐54) × 10 −3 eV.