Significance of distinct electron-correlation effects in determining the (P,T)-odd electric dipole moment of Yb-171

Abstract

The parity and time-reversal violating electric dipole moment (EDM) of Yb-171 is calculated accounting for the electron-correlation effects over the Dirac-Hartree-Fock method in the relativistic Rayleigh-Schrodinger many-body perturbation theory, with the second- [MBPT(2) method] and third-order [MBPT(3) method] approximations, and two variants of all-order relativistic many-body approaches, in the random phase approximation (RPA) and coupled-cluster (CC) method with singles and doubles (CCSD method) framework. We consider electron-nucleus tensor-pseudotensor (T-PT) and nuclear Schiff moment (NSM) interactions as the predominant sources that induce EDM in a diamagnetic atomic system. Our results from the CCSD method to EDM (d(a)) of Yb-171 due to the T-PT and NSM interactions are found to be d(a) = 4.85(6) x 10(-20) <sigma > C-T |e| cm and d(a) = 2.89(4) x 10(-17)S/(|e| fm(3)), respectively, where C-T is the T-PT coupling constant and S is the NSM. These values differ significantly from the earlier calculations. The reason for the same has been attributed to large correlation effects arising through non-RPA type of interactions among the electrons in this atom that are observed by analyzing the differences in the RPA and CCSD results. This has been further scrutinized from the MBPT(2) and MBPT(3) results and their roles have been demonstrated explicitly.