PUB - Publikationen an der Universität Bielefeld

We analyze the temperature dependence of CP violation effects in the StandardModel by determining the effective action of its bosonic fields, obtained afterintegrating out the fermions from the theory and performing a covariantgradient expansion. We find non-vanishing CP violating terms starting at thesixth order of the expansion, both in the C odd/P even and C even/P oddsectors, with coefficients that depend on quark masses, CKM matrix elements,temperature and the magnitude of the Higgs field. The CP violating effects areobserved to decrease rapidly with temperature, which has important implicationsfor the generation of matter-antimatter asymmetry in the early Universe. Ourresults suggest that the cold electroweak baryogenesis scenario may be viablewithin the Standard Model, provided the electroweak transition temperature isat most of order 1GeV.