Relativistic Normal Coupled-Cluster Theory for Accurate Determination of Electric Dipole Moments of Atoms: First application to $^{199}$Hg atom

TL;DR

This paper introduces a relativistic normal coupled-cluster (NCC) method for accurately calculating atomic electric dipole moments, applied to $^{199}$Hg, providing validation and comparison with existing methods and experimental data.

Contribution

The paper extends the NCC method to the relativistic regime for precise EDM calculations, addressing limitations of the RCC approach and applying it to $^{199}$Hg.

Findings

Relativistic NCC results closely match RCC calculations.

Discrepancies with previous results are explained.

Electric dipole polarizability agrees well with measurements.

Abstract

Recent relativistic coupled-cluster (RCC) calculations of electric dipole moments (EDMs) of diamagnetic atoms due to parity and time-reversal violating (P,T-odd) interactions, that are essential ingredients for probing new physics beyond the standard model of particle interactions, differ substantially from the previous theoretical results. It is therefore necessary to perform an independent test of the validity of these results. In view of this, the normal coupled-cluster (NCC) method has been extended to the relativistic regime to calculate the EDMs of atoms by simultaneously incorporating the electrostatic and P,T-odd interactions in order to overcome the shortcomings of the ordinary RCC method. This new relativistic method has been applied to $^{199}$Hg, which currently has a lower EDM limit than that of any other system. The results of our relativistic NCC and self-consistent RCC calculations of the EDM of this atom are found to be close. The discrepancies between these two results on the one hand and those of previous calculations on the other are elucidated. Furthermore, the electric dipole polarizability of this atom, which has computational similarities with the EDM, is evaluated and it is in very good agreement with its measured value.