Search for the electric dipole moment of the electron with thorium monoxide

TL;DR

This paper discusses an experiment using cold thorium monoxide molecules to measure the electron's electric dipole moment, aiming to significantly improve sensitivity and reduce systematic errors compared to previous limits.

Contribution

It introduces a novel experimental approach with ThO molecules, demonstrating potential for three orders of magnitude improvement in eEDM measurement sensitivity.

Findings

Measured the ThO H state lifetime

Produced ThO molecular beam data

Analyzed systematic error rejection properties

Abstract

The electric dipole moment of the electron (eEDM) is a signature of CP-violating physics beyond the Standard Model. We describe an ongoing experiment to measure or set improved limits to the eEDM, using a cold beam of thorium monoxide (ThO) molecules. The metastable $H {}^3\Delta_1$ state in ThO has important advantages for such an experiment. We argue that the statistical uncertainty of an eEDM measurement could be improved by as much as 3 orders of magnitude compared to the current experimental limit, in a first-generation apparatus using a cold ThO beam. We describe our measurements of the $H$ state lifetime and the production of ThO molecules in a beam, which provide crucial data for the eEDM sensitivity estimate. ThO also has ideal properties for the rejection of a number of known systematic errors; these properties and their implications are described.