Scalar-tensor nonlocal gravity

TL;DR

This paper introduces a new scalar-tensor nonlocal gravity theory that explains late-time cosmic acceleration while maintaining consistency with solar system tests and gravitational wave observations.

Contribution

It proposes a pure geometric gravity model based on Deser-Woodard theory with improved observational consistency and parameter determination from theoretical considerations.

Findings

The model explains late-time cosmic acceleration.

It aligns with solar system and gravitational wave tests.

Parameters are fully determined by theory in the simplest case.

Abstract

In order to explain the late-time cosmological acceleration, we propose a new pure geometric gravity based on Deser-Woodard theory, in which the expansion of a matter-dominated universe can be accelerating. This new theory behaves as well as general relativity in solar system and gravitational waves, which is an important improvement over Deser-Woodard nonlocal gravity. Especially, for the simplest case, theoretical considerations determine all the parameters that appear in the Lagrangian.