Neutrino masses and electron--muon--tau-lepton universality

By a simple extension of the standard electroweak gauge group to SU/sub L/(2) x U/sub e/(1) x U/sub μ/(1) x U/sub tau/(1), it is shown that it is possible to get light-neutrino masses in the range of a few electron volts. For this purpose it is necessary that M/sub R/, the mass scale associated with the masses of superheavy neutrinos which carries U/sub i/(1) quantum numbers and which is related to the scale at which e-μ-tau universality is broken, is to be greater than 109 GeV. However, for the solar-neutrino problem M/sub R/ should be in the range of 10/sup 11/--10/sup 12/ GeV. In particular, we obtain two Majorana neutrinos of almost equal mass and one Majorana neutrino (predominantly an electron neutrino) of almost zero mass