Lepton flavour violating processes in an S3-invariant extension of the SM

Abstract

A variety of lepton flavour violating effects related to neutrino oscillations and mixings will be systematically discussed in the framework of a minimal S3-invariant extension of the Standard Model. After a brief review of some results on neutrino masses and mixings, we will give explicit analytical expressions for the matrices of the Yukawa couplings and the results of a computation of the branching ratios of some selected flavour-changing neutral current (FCNC) processes, as well as, the contribution of the exchange of neutral flavour-changing scalars to the anomaly of the magnetic moment of the muon, in terms of the masses of the charged leptons and the neutral Higgs bosons. It will also be shown that the S3 × Z2 flavour symmetry and the strong mass hierarchy of the charged leptons strongly suppress the FCNC processes in the leptonic sector and give a nearly tri-bimaximal neutrino mixing matrix. The contribution of the FCNCs to the anomaly of the magnetic moment of the muon is small but non-negligible.