Nuclear recoil effect on the binding energies in highly charged He-like ions

Abstract

The most precise to-date evaluation of the nuclear recoil effect on the $n=1$\nand $n=2$ energy levels of He-like ions is presented in the range $Z=12-100$.\nThe one-electron recoil contribution is calculated within the framework of the\nrigorous QED approach to first order in the electron-to-nucleus mass ratio\n$m/M$ and to all orders in the parameter $\\alpha Z$. The two-electron $m/M$\nrecoil term is calculated employing the $1/Z$ perturbation theory. The recoil\ncontribution of the zeroth order in $1/Z$ is evaluated to all orders in $\\alpha\nZ$, while the $1/Z$ term is calculated using the Breit approximation. The\nrecoil corrections of the second and higher orders in $1/Z$ are taken into\naccount within the nonrelativistic approach. The obtained results are compared\nwith the previous evaluation of this effect [A. N. Artemyev et al., Phys. Rev.\nA 71, 062104 (2005)].\n