Baryon asymmetry at the weak phase transition in the presence of arbitrary CP violation

Abstract

The interactions of fermions with the domain-wall bubbles produced during a first-order phase transition are considered. An exact solution of the Dirac equation’s fermion propagation is obtained for a wall profile incorporating a position-dependent CP-violating phase. The reflection coefficients through the wall are computed for particles and antiparticles. The asymmetry in the reflection coefficients is especially high (a resonance effect) when the energy and mass of the incident particles are E/m=Δθ/2, where Δθ is the phase variation across the wall width. We compute the chiral-charge flux through the wall surface and the corresponding baryon asymmetry of the Universe. It agrees in sign and magnitude with the observed baryonic excess ϱB/s ≈ 10-10 for a larnge of parameters and CP violation. As a function of Δθ, the ratio ϱb/s reaches a maximum for large values of Δθ (m ≈ mtop).