Flavor and CP symmetries for leptogenesis and neutrinoless double beta decay

Preprint number: CP3-Origins-2016-5 DNRF90 and DIAS-2016-5
Authors: Claudia Hagedorn (CP3-Origins & DIAS) and Emiliano Molinaro (CP3-Origins & DIAS)
External link: arXiv.org

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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 is also not sufficient
in order to fix the sign of $Y_B$. As examples we discuss the series of flavor groups $Delta (3 , n^2)$ and $Delta (6 , n^2)$, $n geq 2$ integer,
and several classes of CP transformations.