QED calculation of electron-electron correlation effects in heliumlike ions

TL;DR

This paper presents a fully relativistic quantum electrodynamics approach to accurately calculate electron-electron correlation effects in highly charged heliumlike ions, including higher-order contributions and various corrections.

Contribution

It introduces a rigorous relativistic method within QED for correlation effects in heliumlike ions, handling degenerate states and combining multiple corrections for precise energy predictions.

Findings

Accurate correlation energy contributions for high-Z heliumlike ions.

Total theoretical predictions match experimental data within uncertainties.

Method effectively handles degenerate and quasi-degenerate states.

Abstract

Fully relativistic approach to evaluate the correlation effects in highly charged ions is presented. The interelectronic-interaction contributions of first and second orders in $1/Z$ are treated rigorously within the framework of bound-state quantum electrodynamics, whereas the calculations of the third- and higher-order contributions are based on the Dirac-Coulomb-Breit Hamiltonian. The developed approach allows one to deal with single as well as degenerate or quasi-degenerate states. We apply this approach to the calculations of the correlation contributions to the $n=1$ and $n=2$ energy levels in heliumlike ions. The obtained contributions are combined with the one-electron and screened QED corrections, nuclear recoil and nuclear polarization corrections to get the total theoretical predictions for the ionization and transition energies in high-$Z$ heliumlike ions.