Theoretical study of ThO for the electron electric dipole moment search

TL;DR

This paper provides a detailed theoretical analysis of ThO molecule properties crucial for electron EDM experiments, including effective electric field and interaction constants, supporting the interpretation of experimental results.

Contribution

The study offers precise calculations of key molecular parameters for ThO, aiding the interpretation of electron EDM measurements and advancing theoretical understanding.

Findings

Calculated effective electric field Eeff = 84 GV/cm

Determined T,P-odd interaction constant W_{T,P} = 116 kHz

Evaluated hyperfine structure and electric-field dependence of g-factors

Abstract

An experiment to search for the electron electric dipole moment (\eEDM) on the metastable $H^3\Delta_1$ state of ThO molecule was proposed and now in the final stage of preparation by the ACME collaboration [http://www.electronedm.org]. To interpret the experiment in terms of \eEDM\ and dimensionless constant $k_{T,P}$ characterizing the strength of the scalar T,P-odd electron-nucleus neutral current interaction, an accurate theoretical study of effective electric field on electron, Eeff, and $W_{T,P}$ constants is required. We report calculation of \Eeff\ (84 GV/cm) and a parameter of T,P-odd scalar neutral currents interaction, $W_{T,P}$ (116 kHz), together with the hyperfine structure constant, molecule frame dipole moment and $H^3\Delta_1\to X^1\Sigma^+$ transition energy, which can serve as a measure of reliability of the obtained \Eeff\ and $W_{T,P}$ values. Besides, our results include a parity assignment and evaluation of the electric-field dependence for the magnetic $g$ factors for the $\Omega$-doublets of $H^3\Delta_1$.