The Serendipity of Electroweak Baryogenesis

TL;DR

This paper explores a novel approach to electroweak baryogenesis by linking Yukawa coupling variations to the Higgs vacuum expectation value, potentially explaining matter-antimatter asymmetry without conflicting with electric dipole moment constraints.

Contribution

It proposes a new mechanism where Yukawa couplings vary during electroweak symmetry breaking, providing a viable source of CP-violation for baryogenesis.

Findings

Yukawa couplings can generate sufficient CP-violation for baryogenesis.

The mechanism avoids severe bounds from Electric Dipole moments.

Baryon asymmetry can naturally reach observed levels.

Abstract

The origin of the matter antimatter asymmetry of the universe remains unexplained in the Standard Model of particle physics. The origin of the flavour structure is another major puzzle of the theory. In this article, we report on recent work attempting to link the two themes through the appealing framework of electroweak baryogenesis. We show that Yukawa couplings of Standard Model fermions can be the source of CP-violation for electroweak baryogenesis if they vary at the same time as the Higgs is acquiring its vacuum expectation value, offering new avenues for electroweak baryogenesis. The advantage of this approach is that it circumvents the usual severe bounds from Electric Dipole moments. These ideas apply if the mechanism explaining the flavour structure of the Standard Model is connected to electroweak symmetry breaking, as motivated for instance in Randall-Sundrum or Composite Higgs models. We compute the resulting baryon asymmetry for different configurations of the Yukawa coupling variation across the bubble wall, and show that it can naturally be of the right order.