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

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 $d_{12}<15\times 10^{-25}e\mathrm{cm}$ and $d_{24}<10\times 10^{-25}e\mathrm{cm}$ 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 ${\mathcal{E}}_{LV}>10^{10}$~GeV.

Submitted to Phys. Rev. Lett