Non-local gravity in D-dimensions: Propagator, entropy and bouncing Cosmology

TL;DR

This paper derives the graviton propagator for a class of non-local, infinite derivative gravity theories in D-dimensions, analyzes their entropy properties in various backgrounds, and explores implications for bouncing cosmology.

Contribution

It provides the first explicit form of the graviton propagator for non-local D-dimensional gravity and examines entropy and bouncing cosmology within this framework.

Findings

The graviton propagator is ghost-free under certain conditions.

De Sitter and Anti-de Sitter entropies are computed and compared.

The study suggests non-singular bouncing cosmology can be consistent with non-local gravity.

Abstract

We present the graviton propagator for an infinite derivative, $D$-dimensional, non-local action, up to quadratic order in curvature around a Minkowski background, and discuss the conditions required for this class of gravity theory to be ghost-free. We then study the gravitational entropy for de-Sitter and Anti-de Sitter backgrounds, before comparing with a recently derived result for a Schwarzschild blackhole, generalised to arbitrary $D$-dimensions, whereby the entropy is given simply by the area law. A novel approach of decomposing the entropy into its $(r, t)$ and spherical components is adopted in order to illustrate the differences more clearly. We conclude with a discussion of de-Sitter entropy in the framework of a non-singular bouncing cosmology.