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Q: Fachverband Quantenoptik und Photonik

Q 60: Precision Spectroscopy of Atoms and Ions VI (joint session A/Q)

Q 60.6: Talk

Thursday, March 13, 2025, 16:00–16:15, KlHS Mathe

Improvement of the bound-electron g-factor theory after completion of two-loop QED calculations — •Bastian Sikora, Vladimir A. Yerokhin, Christoph H. Keitel, and Zoltán Harman — Max Planck Institute for Nuclear Physics, Heidelberg, Germany

The bound-electron g-factor in hydrogenlike ions can be measured and calculated with high precision. In a recent collaboration, the experimental and theoretical g-factors of the bound electron in hydrogenlike tin were found to be in excellent agreement [1]. However, the theoretical uncertainty is orders of magnitude larger than the experimental uncertainty due to uncalculated QED binding corrections at the two-loop level.

In our new work, we report the completed calculation of QED Feynman diagrams with two self-energy loops contributing to the g-factor using the Furry picture approach, i.e. taking into account the electron-nucleus interaction exactly [2]. We demonstrate that our results allow a significant improvement of the total theoretical uncertainty of the bound-electron g-factor.

Our calculations will enable improved tests of QED in planned near-future experiments, e.g. at ALPHATRAP and ARTEMIS, and are relevant for the determination of fundamental constants as well as searches for physics beyond the standard model using heavy ions.

[1] J. Morgner, B. Tu, C. M. König, et al., Nature 622, 53 (2023)

[2] B. Sikora, V. A. Yerokhin, C. H. Keitel and Z. Harman, arXiv:2410.10421v1 [physics.atom-ph]

Keywords: Bound-state QED; High-precision theory; Two-loop Feynman diagrams; QED tests