Tests of Lorentz symmetry in the gravitational sector

TL;DR

This paper reviews tests of Lorentz symmetry in gravity, summarizing experimental constraints within the Standard-Model Extension framework and proposing combined analyses and future improvements.

Contribution

It provides a comprehensive overview of gravitational Lorentz symmetry tests and introduces a combined analysis approach for current experimental data.

Findings

Stringent constraints on Lorentz violation parameters

Analysis of multiple experimental methods yields consistent bounds

Proposals for improved future measurements

Abstract

Lorentz symmetry is one of the pillars of both General Relativity and the Standard Model of particle physics. Motivated by ideas about quantum gravity, unification theories and violations of CPT symmetry, a significant effort has been put the last decades into testing Lorentz symmetry. This review focuses on Lorentz symmetry tests performed in the gravitational sector. We briefly review the basics of the pure gravitational sector of the Standard-Model Extension (SME) framework, a formalism developed in order to systematically parametrize hypothetical violations of the Lorentz invariance. Furthermore, we discuss the latest constraints obtained within this formalism including analyses of the following measurements: atomic gravimetry, Lunar Laser Ranging, Very Long Baseline Interferometry, planetary ephemerides, Gravity Probe B, binary pulsars, high energy cosmic rays,... In addition, we propose a combined analysis of all these results. We also discuss possible improvements on current analyses and present some sensitivity analyses for future observations.