CP-Violating Reflection of High Energy Fermions during a First-Order Phase Transition

Abstract We study the high energy behaviour of fermions hitting a general wall caused by a first-order phase transition. The wall profile is introduced through general analytic and nonanalytic functions. The reflection coefficient is computed in the high energy limit and its connection with the analytic properties of the wall profile function is shown. The high energy behaviour of the fermions hitting the wall is determined either by the leading singularity, i.e., the closest pole to the real axis when the profile function is analytic, or by the first noncontinuous derivative on the real axis in the nonanalytic case. CP-violating wall profiles are studied and it is shown that the respective symmetry properties of the CP-conserving and CP-violating profile functions play an important role on the size of the CP asymmetry.