Radiative seesaw corrections and charged-lepton decays in a model with soft flavour violation

Abstract

We consider the one-loop radiative corrections to the light-neutrino mass matrix and their consequences for the predicted branching ratios of the five lepton-flavour-violating decays ${\ell }_1^{-}\to {\ell }_2^{-}{\ell }_3^{+}{\ell }_3^{-}$ in a two-Higgs-doublet model furnished with the type-I seesaw mechanism and soft lepton-flavour violation. We find that the radiative corrections are very significant; they may alter the predicted branching ratios by several orders of magnitude and, in particular, they may help explain why $\text{mbox}BR({\mu }^{-}\to e^{-}{e}^{+}{e}^{-})$ is strongly suppressed relative to the branching ratios of the decays of the ${\tau }^{-}$. We conclude that, in any serious numerical assessment of the predictions of this model, it is absolutely necessary to take into account the one-loop radiative corrections to the light-neutrino mass matrix.

Comments: 28 pages, 7 figures; v2: one reference added, some minor changes to the text