Lepton triplets and neutrino masses in the standard electroweak model

Abstract

We investigate the addition of a set of $Y=0$ lepton triplets to the standard electroweak theory. We show that, without the addition of a new Higgs-scalar triplet, we can generate both neutrino masses and lepton-number-violating currents while keeping the standard ${W}^{+}\ensuremath{-}Z$ mass ratio. These new lepton-number-violating interactions are naturally much weaker than the standard weak interactions. The new massive lepton triplets are unstable and, with reasonable assumptions on their mass, decay with a lifetime between those of the muon and the $\ensuremath{\tau}$.