Horizon Feedback Inflation

TL;DR

This paper explores how Gibbons-Hawking radiation influences inflation by coupling the inflaton to many spectator fields, leading to a thermal potential and a slow phase transition that can produce sufficient expansion and correct perturbation spectra.

Contribution

It introduces a novel hilltop inflation scenario affected by thermal effects from radiation, reducing fine-tuning needs and explaining natural initial conditions.

Findings

Achieves enough e-folds of inflation with many spectator fields.

Produces the correct spectrum of perturbations.

Demonstrates a natural initial condition setup for inflation.

Abstract

We consider the effect of the Gibbons-Hawking radiation on the inflaton in the situation where it is coupled to a large number of spectator fields. We argue that this will lead to two important effects - a thermal contribution to the potential and a gradual change in parameters in the Lagrangian which results from thermodynamic and energy conservation arguments. We present a scenario of hilltop inflation where the field starts trapped at the origin before slowly experiencing a phase transition during which the field extremely slowly moves towards its zero temperature expectation value. We show that it is possible to obtain enough e-folds of expansion as well as the correct spectrum of perturbations without hugely fine-tuned parameters in the potential (albeit with many spectator fields). We also comment on how initial conditions for inflation can arise naturally in this situation.