Vector models of gravitational Lorentz symmetry breaking

TL;DR

This paper systematically surveys vector models of spontaneous Lorentz symmetry breaking in gravity, identifying a specific class of models that can be analyzed with existing formalism and highlighting unexplored parameter space.

Contribution

It introduces a class of vector models called pseudo-Maxwell that fit the Bailey-Kostelecky formalism and identifies a previously unexamined parameter space for Lorentz breaking.

Findings

Pseudo-Maxwell vector models are compatible with the formalism.

One parameter dimension in the model space remains unexplored.

The formalism can analyze certain vector models of Lorentz symmetry breaking.

Abstract

Spontaneous Lorentz symmetry breaking can occur when the dynamics of a tensor field cause it to take on a non-zero expectation value in vacuo, thereby providing one or more "preferred directions" in spacetime. Couplings between such fields and spacetime curvature will then affect the dynamics of the metric, leading to interesting gravitational effects. Bailey & Kostelecky developed a post-Newtonian formalism that, under certain conditions concerning the field's couplings and stress-energy, allows for the analysis of gravitational effects in the presence of Lorentz symmetry breaking. We perform a systematic survey of vector models of spontaneous Lorentz symmetry breaking. We find that a two-parameter class of vector models, those with kinetic terms we call "pseudo-Maxwell," can be successfully analyzed under the Bailey-Kostelecky formalism, and that one of these two "dimensions" in parameter space has not yet been explored as a possible mechanism of spontaneous Lorentz symmetry breaking.