Small Dirac Neutrino Masses and R-parity from Anomalous U(1) Symmetry

Abstract

We suggest that many of the free parameters in the supersymmetric extensions of the Standard Model can be all linked together to the existence of a non universal U(1) gauge symmetry, which has been spontaneously broken at very high scale. Such a symmetry can easily generate, via non-renormalizable operators, appropriate tree level fermion mass textures as well as the $μ$-term of the Higgs potential. We give a general parametrization of those terms. As an output, R parity breaking terms only appear at a non-renormalizable level and linked to the Yukawa couplings, giving rise to the possibility of having an effective (exact) R parity conservation. As an interesting application of this idea we explore the case where neutrinos are Dirac particles. The scenario can be embedded in an extended SU(5) unification theory where the extra right handed neutrinos are introduced as singlets. Such theory has an exact R parity conservation and sneutrino as LSP.