Impact of spectator fields and non-minimal couplings in spontaneous baryogenesis

TL;DR

This paper explores how non-minimal gravitational couplings and spectator fields influence spontaneous baryogenesis, showing enhancements in baryon asymmetry but still falling short of observed values.

Contribution

It introduces non-minimal gravity-inflaton couplings and scalar spectator fields into spontaneous baryogenesis models, analyzing their effects on baryon asymmetry production.

Findings

Non-minimal coupling increases inflaton decay into fermions.

Spectator fields enhance baryon asymmetry but remain below observed levels.

Overall model modifications improve baryon asymmetry predictions.

Abstract

We investigate the model of spontaneous baryogenesis, considering two extensions to the background paradigm. Firstly, we introduce a non-minimal coupling between gravity and the inflaton, increasing the effective mass squared of the latter. In this way, the inflaton decays more likely into fermion-antifermion pairs during reheating, through baryon-number violating processes. Accordingly, we obtain an overall baryon asymmetry consistent with cosmological observations. Then, we consider a complex scalar spectator field interacting with the inflaton through a biquadratic coupling and non-minimally with gravity, and analyze the impact in terms of baryon asymmetry production. In this scenario too, the background model results significantly enhanced, but the predicted baryon-to-entropy ratio remains smaller than the experimental data.