The Flavor of Cosmology

TL;DR

This paper explores how scalar-dependent Yukawa couplings, called flavons, influence early universe cosmology, providing constraints on flavon models through thermal effects and their impact on Yukawa coupling evolution.

Contribution

It analyzes the cosmological implications of flavons in Froggatt-Nielsen models, including their abundance and thermal corrections, which were previously underexplored.

Findings

Thermal corrections decrease Yukawa couplings in the early universe.

Cosmology constrains flavon models beyond collider reach.

Flavon abundance from freeze-in and oscillations impacts cosmological models.

Abstract

We discuss the cosmology of models in which the standard model Yukawa couplings depend on scalar field(s), often referred to as flavons. We find that thermal corrections of the flavon potential tend to decrease the Yukawa couplings, providing an important input to model-building. Working in the specific framework of Froggatt-Nielsen models, we compute the abundance of flavons in the early universe generated both via freeze-in and from coherent oscillations induced by thermal corrections to their potential, and discuss constraints on flavon models from cosmology. We find that cosmology places important constraints on theories containing flavons even for regions of parameter space inaccessible to collider searches.