Perturbativity vs nonperturbativity in QED-effects for H-like atoms with Zα > 1

Abstract

The behavior of levels near the threshold of the lower continuum in superheavy H-like atoms with [Formula: see text], caused by the interaction [Formula: see text] of the electron’s magnetic anomaly (AMM) dynamically screened at small distances [Formula: see text], with the Coulomb field of atomic nucleus is considered by taking into account the complete dependence of electron’s wave function (WF) on [Formula: see text]. It is shown that the calculation of the contribution caused by [Formula: see text] via both the quark structure and the whole nucleus, considered as a uniformly charged extended Coulomb source, leads to results, which coincide within the accepted precision of calculations. It is also shown that there appears some difference in results between perturbative and nonperturbative methods of accounting for the contribution from [Formula: see text] within the corresponding Dirac equation (DE) in favor of the latter. Moreover, the growth rate of the contribution from [Formula: see text] reaches its maximum at [Formula: see text], while by further increase of [Formula: see text] into the supercritical region [Formula: see text], the shift of levels caused by [Formula: see text] near the lower continuum decreases monotonically to zero. The last result is generalized to the whole self-energy contribution to the shift of levels and so to the possible behavior of radiative QED-effects with virtual photon exchange near the lower continuum.