Pathways to testable leptogenesis

TL;DR

This paper proposes a novel approach to testable leptogenesis by utilizing kinematic effects in a two Higgs doublet model, enabling leptogenesis at accessible energy scales unlike traditional high-scale models.

Contribution

It introduces a new mechanism for testable leptogenesis through kinematic out-of-equilibrium decays in a two Higgs doublet model with neutrino masses from one-loop diagrams.

Findings

Leptogenesis can occur at accessible scales via kinematic effects.

The model achieves sufficient CP asymmetry with larger couplings.

Neutrino masses are generated through one-loop processes.

Abstract

In the conventional seesaw models of neutrino masses, leptogenesis occurs at a very high scale. Three approaches have been discussed in the literature to lower the scale of leptogenesis: mass degeneracy, hierarchy of couplings and three-body decays. We advocate yet another approach to a testable leptogenesis, whereby the decaying particles could go out of equilibrium at an accessible scale due to kinematics, although their couplings to the decay products are larger for generating a desired CP asymmetry. We demonstrate this new possibility for the testable leptogenesis in a two Higgs doublet model where the neutrino masses originate from a one-loop diagram.