Seminarium "High Energy, Cosmology and Astro-particle Physics (HECA)"

In this work we explore a maximally symmetric composite Higgs model featuring a next-to-minimal coset structure, where a pseudoscalar singlet arises alongside the Higgs doublet. Maximal symmetry ensures a finite radiative scalar potential, allowing for a detailed study of electroweak phase transitions in the presence of explicit CP violation. We explore the implications of a CP-violating source in the strong sector, which induces a Z2-asymmetric scalar potential and leads to a non-zero vacuum expectation value for the singlet. After incorporating finite temperature corrections and imposing constraints from current LHC bounds and electric dipole moment measurements, we find that the explicit CP violation drives a strong first-order phase transition. We illustrate that these phase transitions produce gravitational wave signatures that could be observable at future detectors, offering a novel approach to probing composite Higgs models beyond collider experiments. This work highlights the potential of gravitational waves as complementary probes of the strong dynamics in new physics scenarios.