Two-Loop Effects and Current Status of the 4He+ Lamb Shift

TL;DR

This paper reviews recent advances in calculating two-loop binding corrections to the Lamb shift, focusing on helium-4 ions, and provides an updated theoretical estimate of the Lamb shift in 4He+.

Contribution

It presents new calculations of two-loop corrections and updates the theoretical Lamb shift value for 4He+ based on these results.

Findings

Improved theoretical value of the 4He+ Lamb shift.

Enhanced understanding of two-loop binding effects.

Refined calculations for S and P states.

Abstract

We report on recent progress in the treatment of two-loop binding corrections to the Lamb shift, with a special emphasis on S and P states. We use these and other results in order to infer an updated theoretical value of the Lamb shift in 4He+.