A measurement of the magnitude of the electric dipole moment of the electron (eEDM) larger than that predicted by the Standard Model (SM) of particle physics is expected to have a huge impact on the search for physics beyond the SM. Polar diatomic molecules containing heavy elements experience enhanced sensitivity to parity (P) and time-reversal (T)-violating phenomena, such as the eEDM and the scalar–pseudoscalar (S–PS) interaction between the nucleons and the electrons, and are thus promising candidates for measurements. The NL-eEDM collaboration is preparing an experiment to measure the eEDM and S–PS interaction in a slow beam of cold BaF molecules [P. Aggarwal et al., Eur. Phys. J. D 72, 197 (2018)]. Accurate knowledge of the electronic structure parameters, Wd and Ws, connecting the eEDM and the S–PS interaction to the measurable energy shifts is crucial for the interpretation of these measurements. In this work, we use the finite field relativistic coupled cluster approach to calculate the Wd and Ws parameters in the ground state of the BaF molecule. Special attention was paid to providing a reliable theoretical uncertainty estimate based on investigations of the basis set, electron correlation, relativistic effects, and geometry. Our recommended values of the two parameters, including conservative uncertainty estimates, are 3.13 for Wd and 8.29 ± 0.12 kHz for Ws.
Systematic study and uncertainty evaluation of P, T-odd molecular enhancement factors in BaF
Current address: School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China.
Current address: Department of Physics and Astronomy, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
Current address: Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
Note: This paper is part of the JCP Special Collection in Honor of Women in Chemical Physics and Physical Chemistry.
Pi A. B. Haase, Diewertje J. Doeglas, Alexander Boeschoten, Ephraim Eliav, Miroslav Iliaš, Parul Aggarwal, H. L. Bethlem, Anastasia Borschevsky, Kevin Esajas, Yongliang Hao, Steven Hoekstra, Virginia R. Marshall, Thomas B. Meijknecht, Maarten C. Mooij, Kees Steinebach, Rob G. E. Timmermans, Anno P. Touwen, Wim Ubachs, Lorenz Willmann, Yanning Yin, (NL-eEDM Collaboration); Systematic study and uncertainty evaluation of P, T-odd molecular enhancement factors in BaF. J. Chem. Phys. 21 July 2021; 155 (3): 034309. https://doi.org/10.1063/5.0047344
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