Inflation in (Super-)renormalizable Gravity

TL;DR

This paper demonstrates that a super-renormalizable, ghost-free gravity theory can naturally produce Starobinsky inflation and generate curvature perturbations, linking quantum gravity properties with early universe cosmology.

Contribution

It shows that super-renormalizable gravity theories can give rise to Starobinsky inflation and are compatible with ultraviolet quantum gravity requirements.

Findings

Reproduces Starobinsky inflation from super-renormalizable gravity

Shows compatibility of ultraviolet gravity with inflationary dynamics

Analyzes curvature perturbation generation in modified gravity

Abstract

We investigate a (super-)renormalizable and ghost-free theory of gravity, showing that under a natural (exponential) ansatz of the form factor and a suitable truncation it can give rise to the Starobinsky inflationary theory in cosmological frameworks, and thus offering a theoretical justification of its origin. We study the corresponding inflationary evolution and we examine the generation of curvature perturbations, adapting the $f(R)$-like equations in a symmetry-reduced FLRW metric. Furthermore, we analyze how the ultraviolet regime of a simply renormalizable and unitary theory of gravity is also compatible with the Starobinsky action, and hence we show that such a theory could account for an inflationary phase of the Universe in the ultraviolet regime.