Inflation with massive spin-2 ghosts

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.

Automated summary

We investigate the effects of gravitational degrees of freedom on inflationary parameters in a generic model of quadratic gravity coupled to a single scalar. Our findings show that quantum corrections from the massive spin-2 ghost contribute significantly to the effective inflationary potential, enabling the spontaneous breakdown of global scale invariance without the need for additional scalar fields. We compute inflationary parameters and compare them to well-known inflationary models, finding that they fit within the constraints set by the Planck and BICEP/Keck collaborations.