Aspects of Geometric Inflation

TL;DR

This paper analyzes Geometric Inflation, showing it requires very high initial energy density, and proposes a hybrid model with a scalar field that mitigates this issue, leading to a scenario similar to large field inflation.

Contribution

It introduces a scalar field to the Geometric Inflation mechanism, fixing initial energy density issues and revealing a hybrid inflation scenario with reduced scalar field requirements.

Findings

High initial energy density needed for Geometric Inflation

Hybrid model reduces scalar field initial value

Last inflation stage resembles large field inflation

Abstract

We revisit the recently proposed mechanism of Geometric Inflation. On general grounds, we show that obtaining the right amount of inflation demands an exceedingly large initial energy density. We introduce a scalar field and study the combined action of both mechanisms. Besides fixing the aforementioned issue, a cascading process occurs whose last step seems undistinguishable from ordinary large field inflation. Strikingly, the scalar field remains approximately constant while Geometric Inflation rules the dynamics. This ultimately leads to the possibility of reducing the initial value of the scalar field and its excursion. We discuss the main features of this hybrid scenario.