Speaker
Description
I report on recent advances in ab initio QED theory of the 2pj-2s transition energies in Li-like ions and present the most accurate calculations to date for the Li isoelectronic sequence with Z >= 10 [1]. Improved convergence of the calculations was achieved by employing the extended Furry picture, which includes the screening potential nonperturbatively, in addition to the nuclear binding potential. The QED screening effects, the QED electron-structure effects with one and two photon exchanges, and the nuclear recoil effect were calculated rigorously, while higher-order electron-structure and QED screening effects were accounted for by approximate methods. The resulting theoretical predictions improve upon the best previous QED calculations and surpass the accuracy of most existing experimental results.
The achieved accuracy of our QED predictions for Li-like enables the determination of absolute nuclear charge radii through comparison of experimental and theoretical transition energies. I present [2] a proof-of-principle determination of the nuclear charge radii of 208Pb and 209Bi isotopes based on the available experimental data [3-5]. By incorporating constraints derived from electron-scattering data, I demonstrate that the extracted radii are independent of the assumed model of the nuclear charge distribution. Their accuracy is currently limited by experimental precision and, to some extent, by the unknown higher-order QED effects, which contrasts with the muonic-atom determinations limited by the nuclear theory.
[1] V. A. Yerokhin, Z. Harman, and C. H. Keitel, Phys. Rev. A 112, 042801 (2025).
[2] V. A. Yerokhin and B. Ohayon, Phys. Rev. A 113, 012804 (2026).
[3] C. Brandau et al., Phys. Rev. Lett. 91, 073202 (2003).
[4] X. Zhang et al., Phys. Rev. A 78, 032504 (2008).
[5] P. Beiersdorfer et al., Phys. Rev. Lett. 80, 3022 (1998).