New constraints on Lorentz invariance violation from the neutron electric dipole moment

TL;DR

This study tests Lorentz invariance using ultracold neutrons and a neutron electric dipole moment spectrometer, setting new constraints on possible violations at very high energy scales.

Contribution

It introduces a novel method to test Lorentz invariance via neutron EDM measurements and provides the first experimental constraints on direction-dependent effects.

Findings

Limits on modulation amplitudes: d_{12} < 15×10^{-25} e·cm, d_{24} < 10×10^{-25} e·cm

Constraints on Lorentz violation energy scale: > 10^{10} GeV

First experimental bounds on Lorentz invariance violation using neutron EDM

Abstract

We propose an original test of Lorentz invariance in the interaction between a particle spin and an electromagnetic field and report on a first measurement using ultracold neutrons. We used a high sensitivity neutron electric dipole moment (nEDM) spectrometer and searched for a direction dependence of a nEDM signal leading to a modulation of its magnitude at periods of 12 and 24 hours. We constrain such a modulation to $d_{12} < 15 \times 10^{-25} \ e\,{\rm cm}$ and $d_{24} < 10 \times 10^{-25} \ e\,{\rm cm}$ at 95~\% C.L. The result translates into a limit on the energy scale for this type of Lorentz violation effect at the level of ${\cal E}_{LV} > 10^{10}$~GeV.