New test of Lorentz invariance using the MICROSCOPE space mission

TL;DR

This study uses MICROSCOPE space mission data to test Lorentz invariance in matter-gravity interactions, setting new constraints on SME coefficients and enhancing the diversity of experimental bounds.

Contribution

It provides the first constraints on Lorentz violation in matter-gravity couplings from space-based experiments, improving previous bounds by up to two orders of magnitude.

Findings

No evidence of Lorentz violation was found.

Constraints on SME coefficients were significantly improved.

New linear combinations of coefficients were identified, aiding future analyses.

Abstract

We use data from the T-SAGE instrument on board the MICROSCOPE space mission to search for Lorentz violation in matter-gravity couplings as described by the Lorentz violating Standard-Model Extension (SME) coefficients $(\bar{a}_\text{eff})_\mu^w$, where ($\mu = T,X,Y,Z$) and ($w = e,p,n$) for the electron, proton and neutron. One of the phenomenological consequences of a non-zero value of those coefficients is that test bodies of different composition fall differently in an external gravitational field. This is similar to "standard" tests of the universality of free fall, but with a specific signature that depends on the orbital velocity and rotation of the Earth. We analyze data from five measurement sessions of MICROSCOPE spread over a year finding no evidence for such a signature, but setting constraints on linear combinations of the SME coefficients that improve on best previous results by one to two orders of magnitude. Additionally, our independent linear combinations are different from previous ones, which increases the diversity of available constraints, paving the way towards a full decorrelation of the individual coefficients.