Cosmological Aspects of Spontaneous Baryogenesis

TL;DR

This paper explores the cosmological constraints of spontaneous baryogenesis driven by a scalar field, revealing tight parameter restrictions and proposing methods to evade isocurvature perturbation constraints.

Contribution

It provides a model-independent analysis of cosmological constraints on spontaneous baryogenesis and suggests ways to relax isocurvature perturbation limits.

Findings

Cosmological constraints restrict key parameters within a few orders of magnitude.

Minimal quadratic scalar potential scenario faces strong constraints.

Proposed extensions include nonquadratic potentials and dark matter isocurvature compensation.

Abstract

We investigate cosmological aspects of spontaneous baryogenesis driven by a scalar field, and present general constraints that are independent of the particle physics model. The relevant constraints are obtained by studying the backreaction of the produced baryons on the scalar field, the cosmological expansion history after baryogenesis, and the baryon isocurvature perturbations. We show that cosmological considerations alone provide powerful constraints, especially for the minimal scenario with a quadratic scalar potential. Intriguingly, we find that for a given inflation scale, the other parameters including the reheat temperature, decoupling temperature of the baryon violating interactions, and the mass and decay constant of the scalar are restricted to lie within ranges of at most a few orders of magnitude. We also discuss possible extensions to the minimal setup, and propose two ideas for evading constraints on isocurvature perturbations: one is to suppress the baryon isocurvature with nonquadratic scalar potentials, another is to compensate the baryon isocurvature with cold dark matter isocurvature by making the scalar survive until the present.