The effects of the lightest neutrino mass in "flavoured" leptogenesis are investigated in the case 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. 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 obtained. It is shown, in particular, that if the matrix R is real and U-conserving and the lightest neutrino mass m(3) in the case of inverted hierarchical spectrum lies the interval 5 x 10(-4) eV less than or similar to m(3) less than or similar to 7 x 10(-3) eV, the predicted baryon asymmetry can be larger by a factor of similar to 100 than the asymmetry corresponding to negligible m(3) congruent to 0. As consequence, we can have successful thermal leptogenesis for 5 x 10(-6) eV less than or similar to m(3) less than or similar to 5 x 10(-2) eV even if R is real and the only source of CP-violation in leptogenesis is the Majorana and/or Dirac phase(s) in U. (C) 2008 Elsevier B.V. All rights reserved.
Effects of lightest neutrino mass in leptogenesis / Molinaro, E; Petcov, St; Shindou, T; Takanishi, Y. - In: NUCLEAR PHYSICS. B. - ISSN 0550-3213. - 797:1-2(2008), pp. 93-116. [10.1016/j.nuclphysb.2007.12.033]
Effects of lightest neutrino mass in leptogenesis
Petcov, ST;
2008-01-01
Abstract
The effects of the lightest neutrino mass in "flavoured" leptogenesis are investigated in the case 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. 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 obtained. It is shown, in particular, that if the matrix R is real and U-conserving and the lightest neutrino mass m(3) in the case of inverted hierarchical spectrum lies the interval 5 x 10(-4) eV less than or similar to m(3) less than or similar to 7 x 10(-3) eV, the predicted baryon asymmetry can be larger by a factor of similar to 100 than the asymmetry corresponding to negligible m(3) congruent to 0. As consequence, we can have successful thermal leptogenesis for 5 x 10(-6) eV less than or similar to m(3) less than or similar to 5 x 10(-2) eV even if R is real and the only source of CP-violation in leptogenesis is the Majorana and/or Dirac phase(s) in U. (C) 2008 Elsevier B.V. All rights reserved.File | Dimensione | Formato | |
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