Fermion Scattering off a CP-Violating Electroweak BubbleWall II

Abstract

By treating CP-violating interaction as a perturbative term, we solved in a previous paper the Dirac equation in the background of electroweak bubble wall, and obtained the transmission and reflection coefficients for a chiral fermion incident from the symmetric-phase region. We give the transmission and reflection coefficients under the other boundary condition, that is, the case of the fermion incident from the broken-phase region. There hold the respective sets of unitarity relations and also reciprocity relations among them. These relations enable us to obtain a simple form of quantum-number flux through the bubble wall, which is the first order quantity of the CP violation. A factor in the integrand of the flux, which originates from the CP violation, is very sensitive to the functional form of the CP-violating phase. The absolute value of this factor is found to decrease as $m_0/a$ increases for $m_0/a {}~\roughly{>}~1$, where $1/a$ is the wall thickness and $m_0$ the fermion mass near the critical temperature.