Flavor and CP symmetries for leptogenesis and 0nubb decay

TL;DR

This paper analyzes how flavor and CP symmetries influence leptogenesis and neutrinoless double beta decay, constraining CP phases and predicting baryon asymmetry and effective neutrino mass.

Contribution

It provides a comprehensive framework linking flavor and CP symmetries to leptogenesis and 0νββ decay predictions, with detailed analysis of specific flavor groups.

Findings

Sign of baryon asymmetry Y_B can be fixed.

Allowed m_ee range can be strongly constrained.

CP asymmetries are dominated by one Majorana phase.

Abstract

We perform a comprehensive analysis of the phenomenology of leptonic low and high energy CP phases in a scenario with three heavy right-handed neutrinos in which a flavor and a CP symmetry are non-trivially broken. All CP phases as well as lepton mixing angles are determined by the properties of the flavor and CP symmetry and one free real parameter. We focus on the generation of the baryon asymmetry Y_B of the Universe via unflavored leptogenesis and the predictions of m_ee, the quantity measurable in neutrinoless double beta decay. We show that the sign of Y_B can be fixed and the allowed parameter range of m_ee can be strongly constrained. We argue on general grounds that the CP asymmetries epsilon_i are dominated by the contribution associated with one Majorana phase and that in cases in which only the Dirac phase is non-trivial the sign of Y_B depends on further parameters. In addition, we comment on the case of flavored leptogenesis where in general the knowledge of the CP phases and light neutrino mass spectrum is also not sufficient in order to fix the sign of the CP asymmetries. As examples we discuss the series of flavor groups Delta (3 n^2) and Delta (6 n^2), n >= 2 integer, and several classes of CP transformations.