The charged inflaton and its gauge fields: preheating and initial conditions for reheating

TL;DR

This paper investigates particle production during inflation and preheating in models with charged scalar fields coupled to gauge fields, analyzing primordial field spectra, back-reaction timescales, and setting initial conditions for nonlinear lattice simulations.

Contribution

It provides a detailed analysis of gauge field production, spectra, and initial conditions for nonlinear evolution in charged inflaton models, including observational implications.

Findings

Primordial magnetic fields are too weak to explain galactic magnetic fields.

Charge fluctuations remain within observational bounds.

Back-reaction timescales are identified for nonlinear dynamics onset.

Abstract

We calculate particle production during inflation and in the early stages of reheating after inflation in models with a charged scalar field coupled to Abelian and non-Abelian gauge fields. A detailed analysis of the power spectra of primordial electric fields, magnetic fields and charge fluctuations at the end of inflation and preheating is provided. We carefully account for the Gauss constraints during inflation and preheating, and clarify the role of the longitudinal components of the electric field. We calculate the timescale for the back-reaction of the produced gauge fields on the inflaton condensate, marking the onset of non-linear evolution of the fields. We provide a prescription for initial conditions for lattice simulations necessary to capture the subsequent nonlinear dynamics. On the observational side, we find that the primordial magnetic fields generated are too small to explain the origin of magnetic fields on galactic scales and the charge fluctuations are well within observational bounds for the models considered in this paper.