Seesaw mechanism, Majorana CP-violation, μ→eγ decay, leptogenesis and (ββ)0ν-decay

Abstract

We discuss the lepton flavour violating μ decays, μ→e+γ, etc and thermal leptogenesis in the minimal supersymmetric standard model with flavour universal soft supersymmetry breaking at the cutoff scale and seesaw mechanism with heavy right-handed Majorana neutrinos with hierarchical spectrum of masses, M1≪M2≪M3. For a typical value of the heaviest right-handed Majorana neutrino mass, M3≳5×1013 GeV, and supersymmetry particle masses in the few 100 GeV range, the predicted μ→e+γ decay rate exceeds by few order of magnitude the present experimental upper limit. This problem is avoided if the matrix of neutrino Yukawa couplings has a specific form. The latter leads to a correlation between the baryon asymmetry of the Universe predicted by leptogenesis, BR(μ→e+γ) and the effective Majorana mass in neutrinoless double beta decay.