LFV and Dipole Moments in Models with A4 Flavour Symmetry

TL;DR

This paper analyzes lepton flavor violation, magnetic and electric dipole moments within models featuring A4 flavor symmetry, highlighting the effects of dimension six operators and providing bounds on the reactor angle.

Contribution

It introduces a comprehensive framework for studying LFV and dipole moments in A4-based models, considering both supersymmetric and general cases, with a focus on effective operators.

Findings

Upper limit on the reactor angle of a few percent.

Effects dominated by dimension six operators suppressed by new physics scale.

Universal flavor breaking effects described by spurion vacuum expectation values.

Abstract

It is presented an analysis on lepton flavour violating transitions, leptonic magnetic dipole moments and electric dipole moments in a class of models characterized by the flavour symmetry A4 x Z3 x U(1)_FN, whose choice is motivated by the approximate Tri-Bimaximal mixing observed in neutrino oscillations. A low-energy effective Lagrangian is constructed, 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 of a set of spurions. Two separate cases, a supersymmetric and a general one, are described. An upper limit on the reactor angle of a few percent is concluded.