Boom and Bust Inflation: a Graceful Exit via Compact Extra Dimensions

TL;DR

This paper introduces a novel inflation model utilizing compact extra dimensions, enabling a graceful exit and uniform reheating through bubble self-collision, avoiding flat potentials and super-Planckian fields.

Contribution

It proposes a new inflation mechanism leveraging extra dimensions for a graceful exit and uniform reheating, distinct from traditional flat potential models.

Findings

Enables uniform reheating via bubble self-collision.

Produces an approximately scale-invariant perturbation spectrum.

Requires a bulk field, slow vacuum decay, and large extra dimensions.

Abstract

A model of inflation is proposed in which compact extra dimensions allow a graceful exit without recourse to flat potentials or super-Planckian field values. Though bubbles of true vacuum are too sparse to uniformly reheat the Universe by colliding with each other, a compact dimension enables a single bubble to uniformly reheat by colliding with itself. This mechanism, which generates an approximately scale invariant perturbation spectrum, requires that inflation be driven by a bulk field, that vacuum decay be slow, and that the extra dimension be at least a hundred times larger than the false vacuum Hubble length.