Electron electric dipole moment and electroweak baryogenesis in a complex singlet extension of the Standard Model with degenerate scalars

TL;DR

This paper explores how a complex singlet scalar extension of the Standard Model can facilitate electroweak baryogenesis through CP violation from higher-dimensional operators, while remaining consistent with electron EDM constraints.

Contribution

It demonstrates a novel mechanism where CP violation is transmitted via dimension-5 Yukawa interactions in a degenerate scalar scenario, expanding viable baryogenesis parameter space.

Findings

Degenerate scalar scenario suppresses electron EDM.

Higher-dimensional operators enable CP violation transmission.

Parameter space remains viable under current experimental bounds.

Abstract

We study the possibility of electroweak baryogenesis in the standard model with a complex scalar field, focusing mainly on a degenerate scalar scenario. In our setup, CP violation is provided by dimensional-5 Yukawa interactions involving the complex scalar field. In contrast to previous studies in the literature, we exemplify a case in which a complex phase in the singlet scalar potential is transmitted to the fermion sector via the higher-dimensional operators and drives BAU. We point out that an electric dipole moment of the electron can be suppressed due to the Higgs mass degeneracy and the presence of a new electron Yukawa coupling. Thus, viable parameter space for electroweak baryogenesis is still wide open for the latest experimental bound set by the JILA Collaboration.