LAUSR

The interaction ΔUAMM of the Dirac particle anomalous magnetic moment (AMM) with the Coulomb field of a nucleus and its effect on the low-lying atomic levels are studied for Zα > 1 using both perturbative and essentially nonperturbative approaches. The Zα dependence of particle wavefunctions (WFs) is fully taken into account from the beginning. In deriving the ΔUAMM contribution, the nucleus is viewed either as a uniformly charged extended Coulomb source or as a distributed system formed by pointlike u and d quarks. When estimated nonperturbatively, the ΔUAMM-induced effects in the Dirac equation framework prove to be identical for these two cases. At the same time, the ΔUAMM-induced effect is specific in that its perturbative and nonperturbative estimates are very different for Δg ≃ const and practically identical as soon as the dynamical screening of AMM at short distances is taken into account in the Dirac equation.