Neutrino-Lepton Masses, Zee Scalars and Muon g-2

Abstract

Evidence for neutrino oscillations is pointing to the existence of tiny but finite neutrino masses. Such masses may be naturally generated via radiative corrections in models such as the Zee model where a singlet Zee-scalar plays a key role. We minimally extend the Zee model by including a right-handed singlet neutrino \nu_R. The radiative Zee-mechanism can be protected by a simple U(1)_X symmetry involving only the \nu_R and a Zee-scalar. We further construct a class of models with a single horizontal U(1)_FN (a la Frogatt-Nielsen) such that the mass patterns of the neutrinos and leptons are naturally explained. We then analyze the muon anomalous magnetic moment (g-2) and the flavor changing \mu --> e\gamma decay. The \nu_R interaction in our minimal extension is found to induce the BNL g-2 anomaly, with a light charged Zee-scalar of mass 100-300 GeV.