Flavor Cosmology: Dynamical Yukawas in the Froggatt-Nielsen Mechanism

TL;DR

This paper explores how dynamical Yukawa couplings, implemented via the Froggatt-Nielsen mechanism, could link early universe CP violation to electroweak symmetry breaking and matter-antimatter asymmetry, predicting a new scalar below the electroweak scale.

Contribution

It introduces a novel framework connecting flavor dynamics with cosmology using dynamical Yukawas in the Froggatt-Nielsen model, analyzing phenomenology and bounds.

Findings

Dynamical Yukawas can generate sufficient CP violation for baryogenesis.

The scenario predicts a new scalar field below the electroweak scale.

Possible ways to evade the prediction of a light scalar.

Abstract

Can the cosmological dynamics responsible for settling down the present values of the Cabibbo-Kobayashi-Maskawa matrix be related to electroweak symmetry breaking? If the Standard Model Yukawa couplings varied in the early universe and started with order one values before electroweak symmetry breaking, the CP violation associated with the CKM matrix could be the origin of the matter-antimatter asymmetry. The large effective Yukawa couplings which lead to the enhanced CP violation can also help in achieving a strong first-order electroweak phase transition. We study in detail the feasibility of this idea by implementing dynamical Yukawa couplings in the context of the Froggatt--Nielsen mechanism. We discuss two main realizations of such a mechanism, related phenomenology, cosmological and collider bounds, and provide an estimate of the baryonic yield. A generic prediction is that this scenario always features a new scalar field below the electroweak scale. We point out ways to get around this conclusion.