Scalar Extension

The coupling between an axion-like particle (ALP) and the Higgs boson can potentially enhance the electroweak phase transition to be strongly first order. Local electroweak baryogensis, which has been ruled out for the traditioanl Higgs operator, can be effective for the operator that couples the ALP with various anomalies. This paper investigates such a scenario with various ways to probe.

Space-time parity has been proposed as a solution to the strong CP problem for decades. However, electroweak (-like) baryogenesis from the $SU(2)_R \times U(1)_X \to U(1)_Y$ phase transition has been regarded as difficult. This paper investigates the possibility to realize the electroweak (-like) phase transition in such a phase transition, and discuss the resulting cosmological results.