Lepton flavour violation in models with image flavour symmetry Original Research Article

We analyze lepton flavour violating transitions, leptonic magnetic dipole moments (MDMs) and electric dipole moments (EDMs) in a class of models characterized by the flavour symmetry image, whose choice is motivated by the approximate tri-bimaximal mixing observed in neutrino oscillations. We construct the relevant low-energy effective Lagrangian where these effects are dominated by dimension six operators, suppressed by the scale M of new physics. All the flavour breaking effects are universally described by the vacuum expectation values image of a set of spurions. We separately analyze both a supersymmetric and a general case. While the observed discrepancy image in the anomalous MDM of the muon suggests M of order of a few TeV, several data require M above 10 TeV, in particular the limit on EDM of the electron. In the general case also the present limit on image requires image, at least. The branching ratios for image, image and image are all expected to be of the same order. In the supersymmetric case the constraint from image is softened and it can be satisfied by a smaller scale M. In this case both the observed image and the current bound on image can be satisfied, at the price of a rather small value for image, of the order of a few percents, that reflects on a similar value for image.