title: Calculation of the one- and two-loop lamb shift for arbitrary excited hydrogenic states.
abstract: General expressions for quantum electrodynamic corrections to the one-loop self-energy [of order alpha(Zalpha)6] and for the two-loop Lamb shift [of order alpha2(Zalpha)6] are derived. The latter includes all diagrams with closed fermion loops. The general results are valid for arbitrary excited non-S hydrogenic states and for the normalized Lamb shift difference of states, defined as Delta N = n3deltaE(nS) - delta E(1S). We present numerical results for one-loop and two-loop corrections for excited S, P, and D states. In particular, the normalized Lamb shift difference of states is calculated with an uncertainty of order 0.1 kHz.
authors.affiliation: Department of Physics, University of Alberta, Edmonton, AB, Canada T6G 2J1.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Czarnecki
authors.forename: Ulrich D
authors.initials: UD
authors.lastname: Jentschura
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Pachucki