Publication at Faculty of Mathematics and Physics |
2021
Abstract
We present a derivation of the last unknown part of the alpha(7)m contribution to the Lamb shift of a two-electron atom, induced by the radiative QED effects beyond the Bethe logarithm. This derivation is performed in the framework of nonrelativistic quantum electrodynamics and is valid for the triplet (spin S = 1) atomic states.
The obtained formulas are free from any divergences and are suitable for a numerical evaluation. This opens a way for a complete numerical calculation of the alpha(7)m QED effects in helium, which will allow an accurate determination of the nuclear charge radius from measurements of helium transition frequencies.