FERMION MASSES, SU(2)LXU(1)Y, AND THE SOLAR-NEUTRINO PROBLEM

The connection between fermion mass generation in the standard model (SM) and matter resonant oscillation [Mikheyev-Smirnov-Wolfenstein (MSW)] solutions to the solar- and atmospheric-neutrino deficits is examined. Given our lack of understanding of the wide range of values spanned by fermion masses, as emphasized by the heaviness of the top quark, it is not impossible that fermions obtain their masses in a manner unrelated to electroweak symmetry breaking. masses in a manner unrelated to electroweak symmetry breaking. if this is the case, then, within the context of the simplest possible extension of the SM, adding only right-handed neutrino fields, we emphasize that the MSW solution to both the above deficits can be realized via active <--> sterile oscillations, with both small and large vacuum mixing angles. In the large-angle case, a flux in the vicinity of 40-50 solar neutrino units is expected in the Gallium experiments, along with a suppressed neutral current event rate in the Sudbury Neutrino Observatory detector.