Renormalization effects on neutrino masses and mixing in a string-inspiredSU(4)×SU(2)L×SU(2)R×U(1)Xmodel

Abstract

We discuss renormalization effects on neutrino masses and mixing angles in a supersymmetric string-inspired $\mathrm{SU}(4)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(2{)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(2{)}_{R}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1{)}_{X}$ model, with matter in fundamental and antisymmetric tensor representations and singlet Higgs fields charged under the anomalous $\mathrm{U}(1{)}_{X}$ family symmetry. The quark, lepton and neutrino Yukawa matrices are distinguished by different Clebsch-Gordan coefficients. The presence of a second $\mathrm{U}(1{)}_{X}$ breaking singlet with fractional charge allows a more realistic, hierarchical light neutrino mass spectrum with bi-large mixing. By numerical investigation we find a region in the model parameter space where the neutrino mass-squared differences and mixing angles at low energy are consistent with experimental data.