Anisotropic cubic curvature couplings

TL;DR

This paper investigates cubic curvature couplings within an effective field theory framework, revealing nonlinear effects and potential violations of the Weak Equivalence Principle, with implications for solar-system and binary-pulsar tests.

Contribution

It introduces a novel analysis of cubic curvature couplings in gravity, focusing on nonlinear effects and their observational signatures in various gravitational tests.

Findings

No linearized gravity modifications from the coefficients.

Effects depend on the internal structure of bodies, indicating WEP violation.

Binary-pulsar and short-range tests are highly sensitive to these effects.

Abstract

To complement recent work on tests of spacetime symmetry in gravity, cubic curvature couplings are studied using an effective field theory description of spacetime-symmetry breaking. The associated mass dimension 8 coefficients for Lorentz violation studied do not result in any linearized gravity modifications and instead are revealed in the first nonlinear terms in an expansion of spacetime around a flat background. We consider effects on gravitational radiation through the energy loss of a binary system and we study two-body orbital perturbations using the post-Newtonian metric. Some effects depend on the internal structure of the source and test bodies, thereby breaking the Weak Equivalence Principle for self-gravitating bodies. These coefficients can be measured in solar-system tests, while binary-pulsar systems and short-range gravity tests are particularly sensitive.