Inflation with Massive Spin-2 Ghosts

TL;DR

This paper explores how quantum effects from massive spin-2 ghosts in quadratic gravity influence inflation, leading to viable models consistent with current observational constraints.

Contribution

It demonstrates that massive spin-2 ghosts can generate significant quantum corrections that enable spontaneous scale invariance breaking without extra scalars.

Findings

Quantum corrections from spin-2 ghosts affect inflationary potential.

Models fit well within Planck and BICEP/Keck observational constraints.

Spontaneous scale invariance breaking achieved without additional scalars.

Abstract

We consider a generic model of quadratic gravity coupled to a single scalar and investigate the effects of gravitational degrees of freedom on inflationary parameters. We find that quantum corrections arising from the massive spin-2 ghost generate significant contributions to the effective inflationary potential and allow for a realization of the spontaneous breakdown of global scale invariance without the need for additional scalar fields. We compute inflationary parameters, compare the resulting predictions to well-known inflationary models, and find that they fit well within the Planck and BICEP/Keck collaboration's constraints on inflation.