Relativistic recoil, electron-correlation, and QED effects on the $2p_j$-$2s$ transition energies in Li-like ions

The relativistic nuclear recoil, higher-order interelectronic-interaction, and screened QED corrections to the transition energies in Li-like ions are evaluated. The calculation of the relativistic recoil effect is performed to all orders in $1/Z$. The interelectronic-interaction correction to the transition energies beyond the two-photon-exchange level is evaluated to all orders in $1/Z$ within the Breit approximation. The evaluation is carried out employing the large-scale configuration-interaction Dirac-Fock-Sturm method. The rigorous calculation of the complete gauge invariant sets of the screened self-energy and vacuum-polarization diagrams is performed utilizing a local screening potential as the zeroth-order approximation. The theoretical predictions for the $2p_j$-$2s$ transition energies are compiled and compared with available experimental data in the range of the nuclear charge number $Z=10$–60.

Figure 1

Relative values (in $\%$) of the individual contributions to the mass shift coefficient $K$ for the $2p_{1/2}$-$2s$ and $2p_{3/2}$-$2s$ transitions in Li-like ions. The dotted line represents the relative contribution of the electron-electron interaction, the dashed line denotes the relativistic correction, and the dashed-dotted line indicates the QED correction.

Figure 2

Feynman diagrams representing the screened SE (a–c) and VP (d–f) corrections in the extended Furry representation. The wavy line indicates the photon propagator, the triple line displays the electron propagators in the effective potential, and the double line indicates the electron propagators in the Coulomb field of the nucleus. The symbol $\otimes$ represents the extra interaction term associated with the local screening potential.