Electroweak Baryogenesis in the Next to Minimal Supersymmetric Model

TL;DR

The paper investigates electroweak baryogenesis within the NMSSM by examining whether the electroweak phase transition can be strongly first-order to prevent sphaleron washout. It builds a finite-temperature effective potential with tree-level cubic terms in the Higgs-singlet sector, uses RG running from a SUSY-breaking scale near 1 TeV, and scans NMSSM parameters under experimental constraints. It introduces a tunneling-based criterion for the critical temperature and compares it with a curvature-based criterion, finding that about half of viable parameter sets yield a strong first-order transition. The results indicate NMSSM can accommodate electroweak baryogenesis, with negative mu and lighter Higgs masses correlating with higher baryon preservation, and highlight the role of tree-level cubic terms compared with MSSM.

Abstract

In the electroweak phase transition there arises the problem of baryon number washout by sphaleron transitions, which can be avoided if the phase transition is strongly enough first order. The minimal supersymmetric standard model has just two Higgs doublets H1 and H2, while the next to minimal model, NMSSM, has an additional singlet, N, this latter giving rise to the helpful feature that the Higgs potential contains a tree level trilinear field term. We use the tunneling criterion for the existence of a first order electroweak phase change. A quantitative statistical analysis indicates that with parameters of the NMSSM satisfying the experimental constraints a strong first order phase change occurs in about 50% of cases.