Leptogenesis from a feebly interacting dark matter sector

TL;DR

This paper explores a leptogenesis mechanism involving a feebly interacting dark sector and right-handed neutrinos, enabling baryon asymmetry generation at relatively low neutrino masses without degeneracy.

Contribution

It introduces a novel leptogenesis scenario with a dark sector and charged scalar, allowing baryogenesis at 10 TeV neutrino masses without degeneracy.

Findings

Dark sector interactions produce correct relic density.

CP asymmetry arises from right-handed neutrino decays involving scalar S.

Baryon asymmetry generated at 10 TeV neutrino masses.

Abstract

We perform an analysis of leptogenesis in the context of a simple extension of the Standard Model by two fermions; one charged ($\chi $) and one neutral ($\psi$), in addition to three right-handed neutrinos, $N_i$, interacting through a charged gauge singlet scalar $S$. The dark sector ($\chi$, $\psi$ and $S$) interacts feebly and produces a relic density consistent with measurements. The decay of right-handed neutrinos into the charged scalar $S$ and lepton provides an additional source of CP asymmetry, along with contributing through the virtual exchange of $S$ in the standard decay channel. With this the out-of-equilibrium decay of right-handed neutrinos, combined with lepton number changing scattering processes can generate the required baryon asymmetry of the universe even for right-handed neutrino masses in 10 TeV region, without requiring neutrinos to have degenerate masses.