Nuclear-polarization contribution to the Lamb shift in actinide nuclei.

Abstract

The contribution of nuclear polarization to the Lamb shifts of bound electrons in the 1${\mathit{s}}_{1/2}$, 2${\mathit{s}}_{1/2}$, and 2${\mathit{p}}_{1/2}$ states is considered for various even-A nuclei (230\ensuremath{\le}A\ensuremath{\le}252 with 90\ensuremath{\le}Z\ensuremath{\le}98). Utilizing the concept of effective photon propagators with nuclear polarization insertions, the effective self-energy shifts due to virtual excitation of collective nuclear rotational and vibrational states and of the dominant giant dipole resonance are calculated. The formalism is extended to odd-Z nuclei for which the effective interaction is derived within the single-particle approach. While the corresponding energy shifts of the 1${\mathit{s}}_{1/2}$ state represent a considerable correction, the contribution to the 2s-2p splitting is comparable to the current accuracy of high-precision experiments.