Post-Newtonian parameters and constraints on Einstein-aether theory

TL;DR

This paper investigates Einstein-aether theory, a Lorentz-violating gravity model, analyzing observational and theoretical constraints to identify parameter regions consistent with current tests and stability conditions.

Contribution

It provides the first comprehensive analysis of post-Newtonian parameters combined with other constraints for Einstein-aether theory.

Findings

A large parameter space region satisfies all constraints.

Post-Newtonian parameters are consistent with observational limits.

The theory remains stable and positive-energy within this region.

Abstract

We analyze the observational and theoretical constraints on ``Einstein-aether theory", a generally covariant theory of gravity coupled to a dynamical, unit, timelike vector field that breaks local Lorentz symmetry. The results of a computation of the remaining post-Newtonian parameters are reported. These are combined with other results to determine the joint post-Newtonian, vacuum-Cerenkov, nucleosynthesis, stability, and positive-energy constraints. All of these constraints are satisfied by parameters in a large two-dimensional region in the four-dimensional parameter space defining the theory.