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A: Fachverband Atomphysik

A 15: Poster – Highly Charged Ions and their Applications

A 15.7: Poster

Tuesday, March 3, 2026, 17:00–19:00, Philo 1. OG

Lamb shift and g-factor shift calculations due to vacuum polarization in s states — •Jay Dipakbhai Solanki, Zoltán Harman, and Christoph H. Keitel — Max-Planck-Institut für Kernphysik, Heidelberg, Germany

Two-loop vacuum polarization contributions to the Lamb shift and the bound-electron g factor are calculated with perturbative quantum electrodynamics (QED) and some concepts from relativistic quantum mechanics. The g factor – or magnetic moment – of an electron bound in the strong Coulomb potential of a nucleus can nowadays be measured to an astonishing accuracy [1], enabling QED tests at the two-loop level. The Källén-Sabry potential describing certain diagrams is rederived using the optical theorem. The corresponding g factor shifts are calculated analytically from the expectation value of the potential using some simple properties of the Dirac equation. The results reproduce and extend corrections derived in the framework of nonrelativistic QED. — [1] J. Morgner, B. Tu, C. M. König, et al., Nature 622, 53 (2023).

Keywords: Lamb shift; bound-electron g-factor; two-loop vacuum polarization; optical theorem