Systematic study of relativistic and chemical enhancements of $\mathcal{P,T}$-odd effects in polar diatomic radicals

TL;DR

This study systematically analyzes relativistic and chemical factors affecting $ ext{P,T}$-odd effects in polar diatomic radicals, providing insights into enhancements of these effects relevant for fundamental symmetry violation experiments.

Contribution

It introduces a combined numerical and analytical approach to evaluate relativistic and chemical enhancements of $ ext{P,T}$-odd effects in diatomic molecules, and proposes an analytic measure for disentangling these effects.

Findings

Relativistic enhancement factors are critically examined and discussed.

Scaling relations from atomic theory are compared with numerical results.

An analytic measure for disentangling $ ext{P,T}$-odd effects is proposed.

Abstract

Polar diatomic molecules that have, or are expected to have a $^2\Sigma_{1/2}$-ground state are studied systematically with respect to simultaneous violation of parity $\mathcal{P}$ and time-reversal $\mathcal{T}$ with numerical methods and analytical models. Enhancements of $\mathcal{P,T}$-violating effects due to an electric dipole moment of the electron (eEDM) and $\mathcal{P,T}$-odd scalar-pseudoscalar nucleon-electron current interactions are analyzed by comparing trends within columns and rows of the periodic table of the elements. For this purpose electronic structure parameters are calculated numerically within a quasi-relativistic zeroth order regular approximation (ZORA) approach in the framework of complex generalized Hartree-Fock (cGHF) or Kohn-Sham (cGKS). Scaling relations known from analytic relativistic atomic structure theory are compared to these numerical results. Based on this analysis, problems of commonly used relativistic enhancement factors are discussed. Furthermore the ratio between both $\mathcal{P,T}$-odd electronic structure parameters mentioned above is analyzed for various groups of the periodic table. From this analysis an analytic measure for the disentanglement of the two $\mathcal{P,T}$-odd electronic structure parameters with multiple experiments in dependence of electronic structure enhancement factors is derived.