Radiative energy shifts induced by local potentials

We study a specific correction to the Bethe logarithm induced by potentials which are proportional to a Dirac-delta function in coordinate space ('local potentials'). Corrections of this type occur naturally in the calculation of various self-energy corrections to the energy of bound states. Examples include logarithmic higher-order binding corrections to the two-loop self-energy, vacuum-polarization induced corrections to the self-energy and radiative corrections induced by the finite size of the nucleus. We obtain results for excited S and P states and find that the dependence of the corrections on the principal quantum number is remarkable. For the ground state, we find a small modification as compared to previously reported results. Our results are based on mathematical techniques for the treatment of quantum electrodynamic bound states introduced discussed previously by Jentschura and Pachucki.