1208.5609 (Tomas Brauner et al.)

Computing the temperature dependence of effective CP violation in the
standard model    [PDF]

Tomas Brauner, Olli Taanila, Anders Tranberg, Aleksi Vuorinen

CP violation in the standard model originates from the Cabibbo-Kobayashi-Maskawa mixing matrix. Upon integrating all fermions out of the theory, its effects are captured by a series of effective nonrenormalizable operators for the bosonic gauge and Higgs fields. We compute the CP-violating part of the effective action to the leading nontrivial, sixth order in the covariant gradient expansion as a function of temperature. In the limit of zero temperature, our result addresses the discrepancy between two independent calculations existing in the literature [1,2]. We find that CP violation in the standard model is strongly suppressed at high temperature, but that at T<1GeV it may be relevant for certain scenarios of baryogenesis. We also identify a selected class of operators at the next, eighth order and discuss the convergence of the covariant gradient expansion.

View original: http://arxiv.org/abs/1208.5609