Neutrino mass anarchy and leptogenesis

TL;DR

This paper explores leptogenesis within neutrino mass anarchy models, analyzing both type-I and type-II seesaw mechanisms with a focus on flavor effects and random neutrino matrices.

Contribution

It introduces a fully general anarchy scenario for neutrino mass models and incorporates flavor effects into leptogenesis analysis.

Findings

Revisits leptogenesis in type-I seesaw with random matrices and flavor effects.

Extends analysis to type-II seesaw with scalar triplet decays.

Provides a comprehensive framework for neutrino mass anarchy and leptogenesis.

Abstract

In this paper, we investigate leptogenesis under the neutrino mass anarchy hypothesis in both type-I and type-II seesaw models. We first revisit the corresponding study in the type-I seesaw framework with two improvements: in contrast to Ref.[25], where an approximate $U(1)$ flavor symmetry was imposed to ensure sizable hierarchies among the right-handed neutrino masses and Yukawa couplings, we adopt a fully general anarchy scenario with completely random and structureless neutrino mass and Yukawa matrices; moreover, given the crucial role of lepton flavors in both the generation and washout of the lepton asymmetry, flavor effects are consistently incorporated throughout our analysis. We then extend our investigation to the type-II seesaw framework, in which leptogenesis proceeds via the out-of-equilibrium decays of a scalar triplet.