NuTeV anomaly, lepton universality, and nonuniversal neutrino-gauge couplings

Abstract

In previous studies we found that models with flavor-universal suppression of the neutrino-gauge couplings are compatible with NuTeV and Z-pole data. In this paper we expand our analysis to obtain constraints on flavor-dependent coupling suppression by including lepton universality data from W, τ, π and K decays in fits to model parameters. We find that the data are consistent with a variety of patterns of coupling suppression. In particular, in scenarios in which the suppression arises from the mixing of light neutrinos with heavy gauge singlet states (neutrissimos), we find patterns of flavor-dependent coupling suppression which are also consistent with constraints from µ → eγ.