Neutrino mass and proton decay in a U(1)R-symmetric model

Abstract

We study a U(1)R-symmetric extension of the supersymmetric standard model with supersymmetry breaking in the visible as well as hidden sectors. Specifically, we study U(1)R-breaking effects parameterized by the gravitino mass. A special R-charge assignment of right-handed neutrinos allows us to have neutrino Yukawa couplings with the R-charged Higgs field, which develops a tiny vacuum expectation value after the inclusion of U(1) R-symmetry breaking. Even with O(1) Yukawa couplings, a suitable size of Dirac neutrino mass can be generated if the gravitino mass is very small, m3/2 = 1-10 eV. Our flipped R-charge assignment also allows a new type of dimension-five operator that can induce proton decay. It turns out that the proton stability mildly constrains the allowed range of the gravitino mass: A gravitino heavier than 10 keV can evade the proton decay constraint as well as cosmological ones. In this case, the largest neutrino Yukawa coupling is comparable to the electron Yukawa. We also calculate the mass of the pseudo goldstino and its mixing with neutralinos, and briefly discuss its implications in cosmology and Higgs phenomenology. © The Author(s) 2013.