Charged Lepton Decays L_i to L_j + gamma, Leptogenesis CP-Violating Parameters and Majorana Phases

We analyse the dependence of the rates of the LFV charged lepton decays mu to e + gamma, tau to e + gamma, tau to mu + gamma (l_i to l_j + gamma) and their ratios, predicted in the class of SUSY theories with see-saw mechanism of nu-mass generation and soft SUSY breaking with universal boundary conditions at the GUT scale, on the Majorana CP-violation phases in the PMNS neutrino mixing matrix and the ``leptogenesis'' CP-violating (CPV) parameters. The case of quasi-degenerate in mass heavy Majorana neutrinos is considered. The analysis is performed for normal hierarchical (NH), inverted hierarchical (IH) and quasi-degenerate (QD) light neutrino mass spectra. We show, in particular, that for NH and IH nu-mass spectrum and negligible lightest neutrino mass, all three l_i to l_j + gamma decay branching ratios, BR(l_i to l_j + gamma), depend on one Majorana phase, one leptogenesis CPV parameter and on the 3-neutrino oscillation parameters; if the CHOOZ mixing angle theta_13 is sufficiently large, they depend on the Dirac CPV phase in the PMNS matrix. The ``double ratios'' R(21/31) sim BR(mu to e + gamma)/BR(tau to e + gamma) and R(21/32) sim BR(mu to e + gamma)/BR(tau to mu + gamma) are determined by these parameters. The same Majorana phase enters into the NH and IH expressions for the effective Majorana mass in neutrinoless double beta decay, .Comment: 27 pages, 5 figures, version to be published in Physical Review

CP Violation and Lightest Neutrino Mass Effects in Thermal Leptogenesis

Effects of the lightest neutrino mass in "flavoured" leptogenesis when the CP-violation necessary for the generation of the baryon asymmetry of the Universe is due exclusively to the Dirac and/or Majorana phases in the neutrino mixing matrix $U$ are discussed. The type I see-saw scenario with three heavy right-handed Majorana neutrinos having hierarchical spectrum is considered. The "orthogonal" parametrisation of the matrix of neutrino Yukawa couplings, which involves a complex orthogonal matrix $R$, is employed. Results for light neutrino mass spectrum with normal and inverted ordering (hierarchy) are reviewed.Comment: To appear in the proceedings of DISCRETE'08, Symposium on Prospects in the Physics of Discrete Symmetries, IFIC, Valencia, Spain, 11-16 December 200