CP Violation and Lightest Neutrino Mass Effects in Thermal Leptogenesis

TL;DR

This paper investigates how the lightest neutrino mass influences flavored leptogenesis, emphasizing the role of CP-violation from neutrino phases within a type I see-saw framework with hierarchical heavy neutrinos.

Contribution

It analyzes the impact of the lightest neutrino mass on leptogenesis driven solely by CP-violating phases in the neutrino mixing matrix, using the orthogonal parametrization.

Findings

Light neutrino mass affects the efficiency of leptogenesis.

CP-violation from Dirac and Majorana phases can generate the baryon asymmetry.

Results differ for normal and inverted neutrino mass hierarchies.

Abstract

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.