Gravitational dynamics in Higgs inflation: Preinflation and preheating with an auxiliary field

TL;DR

This paper explores the dynamics of Higgs inflation with an auxiliary field, revealing how parametric resonances can lead to structure formation and confirming the robustness of inflation under complex initial conditions.

Contribution

It introduces a full General Relativity analysis of Higgs inflation with an auxiliary field, demonstrating energy transfer mechanisms and structure formation during preinflation and preheating.

Findings

Parametric resonances transfer energy effectively between fields.

Large under/over-densities can form, leading to potential compact objects.

Non-minimal coupling stabilizes the inflaton and reduces perturbation effects.

Abstract

The dynamics of both the preinflationary and the preheating epochs for a model consisting of a Higgs inflaton plus an additional auxiliary field are studied in full General Relativity. The minimally coupled auxiliary field allows for parametric-type resonances that successfully transfer energy from the inflaton condensate to particle excitations in both fields. Depending on the interaction strengths of the fields, the broad resonance periods lead to structure formation consisting of large under/over-densities, and possibly the formation of compact objects. Moreover, when confronting the same model to multi-field inhomogeneous preinflation, the onset of inflation is shown to be a robust outcome. At relatively large Higgs values, the non-minimal coupling acts as a stabilizer, protecting the dynamics of the inflaton, and significantly reducing the impact of perturbations in other fields and matter sectors. These investigations further confirm the robustness of Higgs inflation to multi-field inhomogeneous initial conditions, while putting in evidence the formation of complex structures during the reheating.