Baryon asymmetry and dark matter from soft leptogenesis

TL;DR

This paper explores how soft leptogenesis, extended with a dark matter sector, can simultaneously explain baryon asymmetry and dark matter abundance through neutrino decays and coupling dynamics.

Contribution

It introduces a minimal extension of soft leptogenesis incorporating a dark matter sector and analyzes the resulting dark matter production mechanisms and their dependence on coupling strengths.

Findings

In the weak coupling regime, DM particles form the dominant component due to slow annihilations.

Solutions to Boltzmann equations relate DM masses to couplings in the weak coupling case.

Larger couplings lead to asymmetric DM dominance via effective decays into the MSSM sector.

Abstract

The framework for soft leptogenesis minimally extended with a DM sector is studied. A heavy singlet neutrino superfield acts as the source for (s)lepton asymmetry and by coupling to the singlet DM superfield it produces a DM particle density through decays. The nature of DM generated is twofold depending on whether the Yukawa and DM couplings are either small or large. With sufficiently small Yukawa and DM couplings DM annihilations into MSSM particles are slow and as a consequence all DM particles form the DM component. The solutions to Boltzmann equations are given and the dependence between the DM masses and coupling are presented in this weak coupling regime. Also, the behavior of the efficiency of producing asymmetric DM is determined with weak couplings. We note that a different outcome arises if the couplings are larger because then the ADM component is dominant due to the effectiveness of DM decays into the MSSM sector.