New representation of the nonlocal ghost-free gravity theory

TL;DR

This paper introduces a new mathematical representation for ghost-free nonlocal gravity models, enabling broader applications and revealing deviations from general relativity, with potential links to critical gravity.

Contribution

It presents a novel representation of nonlocal gravity actions that extends their applicability and clarifies their infrared behavior and relation to critical gravity models.

Findings

Representation extends applications to generic Einstein spaces and black holes

Infrared behavior causes violation of general relativity limit

Limit can be restored in a conformal frame

Abstract

A new representation is found for the action of the recently suggested ghost-free nonlocal gravity models generating de Sitter or Anti-de Sitter background with an arbitrary value of the effective cosmological constant. This representation allows one to extend applications of these models from maximally symmetric to generic Einstein spaces and black hole solutions, but clearly indicates violation of the general relativistic limit in this class of theories, induced by their infrared behavior. It is shown that this limit can be recovered in a special conformal frame of these theories, and their relation to critical gravity models is also briefly discussed.