Electroweak Baryogenesis

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.

Electroweak (-like) phase transition is expected to happen in the early universe, given the well-known spontaneous gauge symmetry breaking. This phase transition, if of first order, can provide the necessary out-of-equilbrium condition for baryogenesis. Such a phase transition can happen for the SM electroweak symmetry breaking, or any other similar symmetry breaking in BSM gauge group extensions. This project investigates possibilities to achieve electroweak (-like) baryogenesis in different models.

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.

It has been known the electroweak baryogenesis (EWBG) in the minimal SM is suppressed by the large damping rate of the quark quasiparticle in the thermal plasma, due to the strong QCD interaction. Old literatures proposed a possibility that lepton scattering may be capable of generating enough baryon asymmetry since the damping rate could be much smaller. Is this really the case? This paper proposes a model that mimic the SM quark sector with chiral leptons. We investigate the thermodynamics in detail and concluded that it could be only marginally OK to generate the baryon asymmetry from a lepton sector with CKM-like structure.