End of inflation, oscillons and matter-antimatter asymmetry

TL;DR

This paper investigates how the end of inflation can produce matter-antimatter asymmetry through inflaton dynamics, oscillons, and decay processes, potentially explaining the observed baryon asymmetry in the universe.

Contribution

It introduces a detailed analysis of inflaton asymmetry transfer via oscillons in a complex inflation model with a broken U(1) symmetry, supported by lattice simulations and linear analysis.

Findings

Oscillons lock most of the inflaton asymmetry.

Decay of oscillons can generate the observed baryon asymmetry.

Inflaton asymmetry depends on fragmentation and symmetry breaking.

Abstract

The dynamics at the end of inflation can generate an asymmetry between particles and anti-particles of the inflaton field. This asymmetry can be transferred to baryons via decays, generating a baryon asymmetry in our Universe. We explore this idea in detail for a complex inflaton governed by an observationally consistent -"flatter than quadratic"- potential with a weakly broken global U(1) symmetry. We find that most of the inflaton asymmetry is locked in non-topological soliton like configurations (oscillons) produced copiously at the end of inflation. These solitons eventually decay into baryons and generate the observed matter-antimatter asymmetry for a range of model parameters. Through a combination of three dimensional lattice simulations and a detailed linearized analysis, we show how the inflaton asymmetry depends on the fragmentation, the magnitude of the symmetry breaking term and initial conditions at the end of inflation. We discuss the final decay into baryons, but leave a detailed analysis of the inhomogeneous annihilation, reheating and thermalization to future work. As part of our work, we pay particular attention to generating multifield initial conditions for the field fluctuations (including metric perturbations) at the end of inflation for lattice simulations.