Time-delay and Doppler tests of the Lorentz symmetry of gravity

TL;DR

This paper investigates how Lorentz-violating modifications in the Standard-Model Extension affect gravitational time-delay and Doppler signals, providing new theoretical predictions and sensitivity estimates for experiments testing Lorentz symmetry in gravity.

Contribution

It derives the leading Lorentz-violating corrections to time-delay and Doppler signals and analyzes their unique anisotropic, time-dependent signatures in gravitational experiments.

Findings

Lorentz violation introduces anisotropic, time-dependent effects in signals.

Sensitivity estimates for current and future experiments are provided.

Recent Cassini data can constrain Lorentz-violating coefficients.

Abstract

Modifications to the classic time-delay effect and Doppler shift in General Relativity (GR) are studied in the context of the Lorentz-violating Standard-Model Extension (SME). We derive the leading Lorentz-violating corrections to the time-delay and Doppler shift signals, for a light ray passing near a massive body. It is demonstrated that anisotropic coefficients for Lorentz violation control a time-dependent behavior of these signals that is qualitatively different from the conventional case in GR. Estimates of sensitivities to gravity-sector coefficients in the SME are given for current and future experiments, including the recent Cassini solar conjunction experiment.