Spontaneous Leptogenesis with sub-GeV Axion Like Particles

TL;DR

This paper proposes a novel mechanism for spontaneous leptogenesis involving sub-GeV axion-like particles, utilizing an inert Higgs doublet to enable lepton asymmetry generation at lower reheating temperatures, compatible with current experimental searches.

Contribution

It introduces an inert Higgs doublet assisted lepton number violating operator to facilitate leptogenesis with light ALPs at lower temperatures, overcoming previous limitations.

Findings

Enables leptogenesis with sub-GeV ALPs at lower reheating temperatures.

Provides a viable framework compatible with current ALP searches.

Relates lepton asymmetry generation to light ALPs and new operator dynamics.

Abstract

A derivative coupling of an axion like particle (ALP) with a B-L current may lead to the baryon asymmetry of the universe via spontaneous leptogenesis provided a lepton number breaking interaction prevails in thermal equilibrium. Conventionally, such scenario works only for heavy ALPs and high reheating temperature due to the fact that the same lepton number breaking contribution is tied up with neutrino mass generation also. In this work, we propose inert Higgs doublet assisted lepton number violating operator to relieve such tension so as to generate lepton asymmetry (of freeze-in/out type) with a much lower reheating temperature that can accommodate light (sub-GeV) ALPs sensitive to current and future ALP searches.