Towards geometric inflation: the cubic case

TL;DR

This paper introduces a cubic curvature correction to General Relativity that is ghost-free, supports well-behaved black holes, and naturally triggers an inflationary phase in the early universe, smoothly transitioning to a late-time cosmology similar to ΛCDM.

Contribution

It proposes a new cubic gravity model with desirable physical properties and a geometric inflation mechanism, advancing theoretical understanding of early universe dynamics.

Findings

Ghost-free vacuum spectrum with only gravitons

Black hole solutions match Einsteinian cubic gravity

Supports a geometric inflationary mechanism with graceful exit

Abstract

We present an up to cubic curvature correction to General Relativity with the following features: (i) its vacuum spectrum solely consists of a graviton and is ghost-free, (ii) it possesses well-behaved black hole solutions which coincide with those of Einsteinian cubic gravity, (iii) its cosmology is well-posed as an initial value problem and, most importantly, (iv) it entails a geometric mechanism triggering an inflationary period in the early universe (driven by radiation) with a graceful exit to a late-time cosmology arbitrarily close to $\Lambda$CDM.