STANDARD MODEL CP-VIOLATION AND BARYON ASYMMETRY

In CP arguments, we argue against a Standard Model explanation of the baryon asymmetry of the universe in the presence of a first order phas e transition. A CP-asymmetry is found in the reflection coefficients o f quarks hitting the phase boundary created during the electroweak tra nsition. The problem is analyzed both in an academic zero temperature- case and in the realistic finite temperature one. The building blocks are similar in both cases: Kobayashi-Maskawa CP-violation, CP-even pha ses in the reflection coefficients of quarks, and physical transitions due to fermion self-energies. In both cases an effect is present at o rder alpha(W)2 in rate. A regular GIM behavior is found as intuitively expected. In the finite temperature case, a crucial role is played by the damping rate of quasiparticles in a hot plasma, which is a releva nt scale together with M(W) and the temperature. The effect is many or ders of magnitude below what observation requires, and indicates that non-standard physics is indeed needed in the cosmological scenario.