Baryogenesis in the MSSM, nMSSM and NMSSM

TL;DR

This paper assesses electroweak baryogenesis in the MSSM, and its singlet-extended variants NMSSM and nMSSM. It employs the Kadanoff-Baym transport formalism to derive CP-violating sources and diffusion dynamics across a moving bubble wall, linking CP violation, out-of-equilibrium dynamics, and sphaleron processes. The MSSM can generate the baryon asymmetry only in a tightly constrained region requiring nearly degenerate charginos and sizable CP phases, whereas singlet extensions strengthen the electroweak phase transition and introduce new CP-violating sources, relaxing those requirements. The nMSSM in particular allows viable EWBG with a dynamical μ term, thinner bubble walls, and EDM compatibility, highlighting singlet extensions as a promising framework for testable, collider-accessible baryogenesis.

Abstract

We compare electroweak baryogenesis in the MSSM, nMSSM and NMSSM. We comment on the different sources of CP violation, the phase transition and constraints from EDM measurements.

Figures (3)

• Figure 1: The left plot shows the produced BAU in the MSSM for $M_2=200$ GeV. In the right plot, the black area denotes the region in the $(\mu_c, M_2)$ plane, where EWBG is viable.
• Figure 2: The electroweak phase transition in the nMSSM.
• Figure 3: Produced baryon asymmetry in random nMSSM models.