Cold Baryogenesis from first principles in the Two-Higgs Doublet model with Fermions

TL;DR

This paper performs a first-principles numerical study of Cold Baryogenesis within a two-Higgs doublet model, demonstrating that combined CP and P breaking effects can generate a baryon asymmetry, with a tentative asymmetry estimate of up to 3.5×10⁻⁷.

Contribution

It provides the first numerical computation of baryon asymmetry in a two-Higgs doublet model with fermions, highlighting the importance of combined symmetry breaking effects.

Findings

Baryon asymmetry estimated at |η| ≤ 3.5×10⁻⁷.

CP and P breaking effects must be combined to produce asymmetry.

Numerical signal near the limit of computational discernibility.

Abstract

We present a first-principles numerical computation of the baryon asymmetry in electroweak-scale baryogenesis. For the scenario of Cold Baryogenesis, we consider a one fermion-family reduced CP-violating two Higgs-doublet model, including a classical SU(2)-gauge/two-Higgs sector coupled to one quantum left-handed fermion doublet and two right-handed singlets. Separately, the C(CP) breaking of the two-Higgs potential and the C and P breaking of the gauge-fermion interactions do not provide a baryon asymmetry. Only when combined does baryogenesis occur. Through large-scale computer simulations, we compute the asymmetry for one particularly favourable scalar potential. The numerical signal is at the boundary of what is numerically discernible with the available computer resources, but we tentatively find an asymmetry of $|\eta|\leq 3.5\times 10^{-7}$.