Relativistic many-body analysis of the electric dipole moment enhancement factor of 210Fr and associated properties

TL;DR

This paper uses an advanced relativistic coupled-cluster method to accurately calculate the electric dipole moment enhancement factor of 210Fr, providing insights for electron EDM searches and exploring many-body effects in heavy atoms.

Contribution

It develops an improved RCC method for calculating the EDM enhancement factor, including corrections for Breit, QED, and triple excitations, with application to 210Fr.

Findings

Calculated R = 799 with 3% error margin

Found R to be 11% smaller than previous theoretical estimates

Assessed effects of Breit, QED, and triple excitations on R

Abstract

The relativistic coupled-cluster (RCC) method is a powerful many-body method, particularly in the evaluation of electronic wave functions of heavy atoms and molecules, and can be used to calculate various atomic and molecular properties. One such atomic property is the enhancement factor (R) of the atomic electric dipole moment (EDM) due to an electron EDM needed in electron EDM searches. The EDM of the electron is a sensitive probe of CP-violation, and its search could provide insights into new physics beyond the Standard Model, as well as open questions in cosmology. Electron EDM searches using atoms require the theoretical evaluation of R to provide an upper limit for the magnitude of the electron EDM. In this work, we calculate R of 210Fr in the ground state using an improved RCC method, and perform an analysis on the many-body processes occurring within the system. The RCC method allows one to capture the effects of both the electromagnetic interaction and P- and T-violating interactions, and our work develops this method beyond what had been implemented in the previous works. We also perform calculations of hyperfine structure constants, electric dipole transition matrix elements, and excitation energies, to assess the accuracy of R and the success of our improved method. Finally, we present calculations of R with corrections due to Breit interaction effects, approximate quantum electrodynamics (QED) effects, and some leading triple excitation terms added perturbatively, to assess how significantly these terms contribute to the result. We obtain a final value of R = 799, with an estimated 3% error, which is about 11% smaller than a previously reported theoretical calculation.