Lorentz and CPT Tests in Neutron and Storage-Ring EDM Experiments

TL;DR

This paper analyzes Lorentz- and CPT-violating effects in neutron and storage-ring EDM experiments within the Standard-Model Extension (SME). It derives leading-order spin-precession corrections using perturbation theory for confined neutrons and a generalized Bargmann-Michel-Telegdi equation for charged particles in storage rings, establishing explicit relations between EDM observables and SME coefficients. Key results include mappings such as $\Delta \omega_{n, \rm EDM} = 4 d_n E$ and $\Delta \omega_{n, \rm LV} = 4 \widetilde{b}_{F,n}^{303} E$, along with a radial LV spin-precession relation for storage rings, enabling the first constraints on several previously unconstrained SME parameters. The framework allows existing EDM limits to be translated into SME bounds in a Sun-centered frame, guiding future experimental and theoretical efforts to test fundamental symmetries.

Abstract

We investigate Lorentz- and CPT-violating effects in neutron and storage-ring electric dipole moment (EDM) experiments within the framework of the Standard-Model Extension (SME). For neutron EDM experiments, perturbation theory is applied to derive leading-order contributions to the spin precession frequency arising from Lorentz and CPT violation. For storage-ring experiments, a generalized Bargmann-Michel-Telegdi equation is used to determine the corresponding spin-precession modifications. The analysis establishes explicit correspondences between measured EDMs and specific SME coefficients, providing a basis for setting the first limits on several previously unconstrained coefficients for Lorentz violation in future studies.