Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

To provide predictions of the Lamb shift of highly charged ions on the level of accuracy of about
10(-6) has been achieved after exact results for the contributions of all two-photon self-energy
diagrams have been performed. We report on the present status of our Lamb-shift calculations
including all QED-corrections of first- and second-order in the finestructure constant a and all
relevant nuclear effects. An excellent agreement between the most recent experimental data for Lamb
shift of the ls-ground state in hydrogenlike uranium can be stated. This can serve as a sensitive test
of QED in the strongest electric fields accessible in nature. In a second part of this article we report
about an all-order numerical evaluation of the one-photon selfenergy at low nuclear charge (Z =
1,...,5). A sensitive comparison of our numerical approach with analytical approach to the one-photon
selfenergy confirms the consistency of these two different approaches (numerical and analytic) to very
high precision.