Nonlocal theories of gravity: the flat space propagator

TL;DR

This paper derives the flat space propagator for various nonlocal gravity theories, providing insights into their ghost-free and singularity-free properties, and analyzes specific models like f(R) and Gauss-Bonnet.

Contribution

It presents a detailed derivation of the flat space propagator applicable to a broad class of covariant nonlocal gravity theories, including specific models.

Findings

Identification of ghost-free nonlocal gravity models

Analysis of f(R), Gauss-Bonnet, and Weyl-squared theories

Insights into asymptotically free nonlocal theories

Abstract

It was recently found that there are classes of nonlocal gravity theories that are free of ghosts and singularities in their Newtonian limit [PRL, 108 (2012), 031101]. In these proceedings, a detailed and pedagogical derivation of a main result, the flat space propagator for an arbitrary covariant metric theory of gravitation, is presented. The result is applied to analyse f(R) models, Gauss-Bonnet theory, Weyl-squared gravity and the potentially asymptotically free nonlocal theories.