Hyperbolic Inflation

TL;DR

This paper introduces a novel inflationary model utilizing compact hyperbolic extra dimensions with non-minimal coupling, achieving compatibility with observations and predicting a measurable gravitational wave signal.

Contribution

It presents a new inflation scenario based on hyperbolic extra dimensions that decouples the volume from the Kaluza-Klein scale, allowing for high-scale single-field inflation.

Findings

Model fits all current observational data.

Predicts a tensor-to-scalar ratio of about 0.003.

Allows inflation at a scale around 10^{13} GeV.

Abstract

We propose a natural scenario for the cosmological inflation with the non-minimal coupling term invoking compact hyperbolic extra dimensions. Thanks to the unique mathematical properties of compact hyperbolic space, the large volume of extra dimensions, which provides a natural understanding of the proper size of couplings, does not necessarily accompany with the low Kaluza-Klein scale so that the model allows a single field inflation with a scale around $10^{13}$ GeV. The model fulfills all the observed data and predicts a sizable gravitational perturbation, r~0.003.