CP violation and leptogenesis in models with minimal lepton flavour violation

Abstract

We investigate the viability of leptogenesis in models with three heavy right-handed neutrinos, where the charged-lepton and the neutrino Yukawa couplings are the only irreducible sources of lepton-flavour symmetry breaking (minimal lepton flavour violation hypothesis). We show that in this framework a specific type of resonant leptogenesis can be successfully accomplished, whose distinctive feature is the raise of the baryon asymmetry with the mass scale of right-handed neutrinos for M ν ≳ 10 11 GeV . For M ν around and below this scale, the baryon asymmetry tends to be below the experimental range in most of the parameter space of these models (in the limit of one effective light Higgs boson or two Higgs doublets and tan β = O ( 1 ) ). By means of a general effective field theory approach, we analyse the impact of the CP violating phases responsible for leptogenesis on the low-energy FCNC observables and derive bounds on the scale of flavour violating new physics interactions. As a result of the high value of the scale of total lepton-number violation, in this class of models the μ → e γ decay is expected to be close to the present exclusion limit (under the additional assumption of new particles carrying lepton flavour at the TeV scale).