Two-loop electron self-energy in the bound-electron g factor: Diagrams in momentum-coordinate representation

Abstract:

The two-loop electron self-energy correction is one of the most problematic QED effects and, for a long time, was the dominant source of uncertainty in the theoretical prediction of the bound-electron 𝑔 factor in hydrogenlike ions. A major breakthrough was recently achieved by B. Sikora et al. [Phys. Rev. Lett. 134, 123001 (2025)], who calculated this effect without any expansion in the nuclear binding strength parameter 𝑍⁢𝛼 (where 𝑍 is the nuclear charge number and 𝛼 is the fine-structure constant). In this paper we describe our calculations of one of the most difficult parts of the two-loop self-energy, represented by Feynman diagrams that are treated in the mixed momentum-coordinate representation.

V. A. Yerokhin, B. Sikora, Z. Harman, C. H. Keitel, „Two-loop electron self-energy in the
bound-electron g factor: Diagrams in momentum-coordinate representation“, Phys. Rev. A 112, 062806 (2025).

https://journals.aps.org/pra/abstract/10.1103/yflg-7wz4

Related to Project B02