The 16th Particle Physics Phenomenology Workshop

Gravitational waves from CP domain wall collapse and electron EDM in a complex singlet model with dimension-five Yukawa interactions

17 Jun 2026, 14:35

10m

NTHU

Poster presentation Parallel Session R620

Speaker

Hieu The Pham (Department of Physics, National Tsing Hua University)

Description

We study the interplay between gravitational waves (GWs) from domain wall collapse and the electron electric dipole moment (EDM) in a complex singlet extension of the Standard Model with dimension-five Yukawa interactions. In this model, CP-related degenerate vacua lead to the formation of CP domain walls. While the resulting GWs probe the scalar vacuum structure, they do not inherently constitute a CP-violating observable. However, coupling the singlet scalar to fermions makes CP-violating phases observable via EDMs.

We find that current electron EDM bounds already constrain this parameter space, and future sensitivities of $10^{-31}-10^{-32}\,e\,\mathrm{cm}$ will probe regions directly overlapping with the GW signals detectable by SKA and THEIA. Our results highlight the complementarity between GW and EDM observables in probing the singlet scalar sector, providing a coherent picture of its vacuum structure and CP properties.