QUARK AND LEPTON MASS MATRICES FROM HORIZONTAL U(1) SYMMETRY

In the simplest model of horizontal U(1) symmetry with one singlet add ed to the supersymmetric standard model, we systematically reconstruct quark mass matrices from the low-energy data to prove that there are only two mass matrices found by Binetruy et at. The same U(1) symmetry constrains the hierarchical structure of L-violating couplings, from which we build radiative neutrino mass matrices accommodating the sola r and hot dark matter neutrino masses and mixing. We find a few patter ns of acceptable charged lepton and neutrino mass matrices, most of wh ich are consistent with large tan beta similar or equal to m(t)/m(b) o nly.