Low scale leptogenesis in a model with promising $CP$ structure

TL;DR

This paper proposes a simple extension of the standard model that addresses CP issues, enables low-temperature leptogenesis, and introduces an alternative dark matter candidate, all consistent with neutrino mass generation.

Contribution

It introduces a novel model combining CP solutions with low-scale leptogenesis and an alternative dark matter candidate, avoiding the need for resonance effects.

Findings

Leptogenesis can occur at reheating temperatures below 10^9 GeV.

The model integrates the Peccei-Quinn and Nelson-Barr mechanisms.

An alternative dark matter candidate is successfully incorporated.

Abstract

We consider a simple extension of the standard model, which could give a solution to its $CP$ issues through both the Peccei-Quinn mechanism and the Nelson-Barr mechanism. Its low energy effective model coincides with the scotogenic model in the leptonic sector. Although leptogenesis is known not to work well at lower reheating temperature than $10^9$ GeV in simple seesaw and scotogenic frameworks, such low reheating temperature could be consistent with both neutrino mass generation and thermal leptogenesis via newly introduced fields without referring to the resonance effect. An alternative dark matter candidate to axion is prepared as an indispensable ingredient of the model.