STANDARD MODEL CP-VIOLATION AND BARYON ASYMMETRY .1. ZERO-TEMPERATURE

We consider quantum effects in a world with two coexisting symmetry ph ases, unbroken and spontaneously broken, as a result of a first order phase transition. The discrete symmetries of the problem are discussed in general. We compute the exact two-point Green function for a free fermion, when a thin wall separates the two phases. The Dirac propagat or displays both massive and massless poles, and new CP-even phases re sulting from the fermion reflection on the wall. We discuss the possib le quark-antiquark CP-asymmetries produced in the Standard Model (SM) for the academic T = 0 case. General arguments indicate that an effect first appears at order alpha(w) in the reflection amplitude, as the w all acts as a source of momentum and the on-shell one-loop self-energy cannot be renormalized away. The asymmetries stem from the interferen ce of the SM CP-odd couplings and the CP-even phases in the propagator . We perform a toy computation that indicates the type of GIM cancella tions of the problem. The behaviour can be expressed in terms of two u nitarity triangles.