On the quartic curvature gravity in the context of FRW cosmology

TL;DR

This paper investigates fourth-order quantum curvature corrections from superstring theory within FRW cosmology, deriving generalized Friedmann equations that admit non-singular inflationary solutions.

Contribution

It introduces new generalized Friedmann equations incorporating quartic curvature corrections and demonstrates their ability to produce singularity-free inflationary solutions.

Findings

Exact inflationary solutions without spacetime singularities

Ruling out naive Bel-Robinson tensor squared gravity

Impact of superstring-derived quantum corrections on cosmological evolution

Abstract

We consider the purely gravitational fourth-order (in the spacetime curvature) quantum corrections to the Einstein-Hilbert gravity action, coming from superstrings in the leading order with respect to the Regge slope parameter, and study their impact on the evolution of the Hubble scale in the context of the FRW cosmology, in four spacetime dimensions. We propose the generalized Friedmann equations, and rule out the most naive (Bel-Robinson tensor squared) gravity. Our new cosmological equations have exact inflationary solutions without a spacetime singularity.