Electroweak baryogenesis with a pseudo-Goldstone Higgs boson

Abstract

We examine the nature of electroweak Baryogenesis when the Higgs boson's properties are modified by the effects of new physics. We utilize the effective potential to one loop (ring improving the finite temperature perturbative expansion), while retaining parametrically enhanced dimension six operators of $\mathcal{O}({v}^{2}/{f}^{2})$ in the Higgs sector. These parametrically enhanced operators would be present if the Higgs is a pseudo-Goldstone boson of a new physics sector with a characteristic mass scale $\ensuremath{\Lambda}\ensuremath{\sim}\mathrm{TeV}$, a coupling constant $4\ensuremath{\pi}\ensuremath{\ge}g\ensuremath{\ge}1$, and a strong decay constant scale $f=\ensuremath{\Lambda}/g$. We find that generically the effect of new physics of this form allows a sufficiently first order electroweak phase transition so that the produced Baryon number can avoid washing out, and has enhanced effects due to new sources of $CP$ violation. We also improve the description of the electroweak phase transition in perturbation theory by determining the thermal mass eigenstate basis of the standard model gauge boson fields. This improves the calculation of the finite temperature effects through incorporating mixing in the determination of the vector boson thermal masses of the standard model. These effects are essential to determining the nature of the phase transition in the standard model and are of interest in our pseudo-Goldstone Baryogenesis scenario.