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.