Speaker
Description
The bound-electron $𝑔$-factor in heavy highly charged ions can be measured with high precision. However, due to uncalculated two-loop QED binding corrections, the theoretical uncertainty in this regime is orders of magnitude larger than the experimental uncertainty. This was also highlighted in a recent collaborative project, where the comparison of bound-electron $𝑔$-factors in hydrogenlike tin found an excellent agreement between experiment and theory [1].
In our new work, we report a significant improvement of the theoretical uncertainty of the bound-electron $g$-factor in hydrogenlike ions in the high-$Z$ regime, through the complete calculation of QED Feynman diagrams with two self-energy loops (the so-called SESE correction). In this work, we take into account the electron-nucleus interaction exactly [2].
In our previous work, we had presented first partial results for the SESE correction and demonstrated that our calculations are consistent with established free-electron results [3].
Our completed SESE calculation [2] will be highly relevant for improved tests of QED in planned near-future experiments with heavy hydrogenlike ions, e.g. ALPHATRAP at MPIK and ARTEMIS at GSI. Furthermore, our results are relevant for the direct determination of nuclear parameters from bound-electron $g$-factor measurements in heavy ions, the determination of fundamental constants as well as enhanced searches for New Physics.
[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, Phys. Rev. Lett. 134, 123001 (2025)
[3] B. Sikora, V. A. Yerokhin, N. S. Oreshkina, et al., Phys. Rev. Res. 2, 012002(R) (2020).