QED Theory of Transition Probabilities and Line Profiles in Highly Charged Ions

A rigorous QED theory of the spectral line profiles is applied to transition probabilities in few-electron highly charged ions. Interelectron interaction corrections are included as well as radiative corrections. Parity nonconserving (PNC) amplitudes with effective weak interactions between the electrons and nucleus are also considered. QED and interelectron interaction corrections to the PNC amplitudes are derived.     

Asymmetry of the natural line profile for the hydrogen atom

The asymmetry of the natural line profile for transitions in hydrogenlike atoms is evaluated within a QED framework. For the Lyman- alpha 1s-2p absorption transition in neutral hydrogen this asymmetry results in an additional energy shift of 2.929 856 Hz. For the 2s(1/2)-2p(3/2) transition it amounts to -1.512 674 Hz. As a new feature this correction turns out to be process dependent. The quoted numbers refer to the Compton-scattering process.     

Overlapping identical resonances and double radiative interference effects in recombination of heavy multicharged ions

The purely QED effect of double radiative interference in the recombination of electrons with heavy multicharged ions is discussed. Numerical calculations of the corresponding cross sections in the vicinities of the KL ₁₂ M ₁₂ and KM ₁₂ M ₁₂ dielectronic recombination resonances of heliumlike uranium are reported. The possibility of near-future experimental observation of the effect with the Super-EBIT facility is suggested. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 7, 552–556 (10 October 1998) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Effects of QED and Beyond from the Atomic Binding Energy

Atomic binding energies are calculated at utmost precision. A report on the current status of Lamb-shift predictions for hydrogenlike ions, including all quantum electrodynamical corrections to first and second order in the fine structure constant α is presented. All relevant nuclear effects are taken into account. High-precision calculations for the Lamb shift in hydrogen are presented. The hyperfine structure splitting and the g factor of a bound electron in the strong electromagnetic field of a heavy nucleus is considered. Special emphasis is also put on parity violation effects in atomic systems. For all systems possible investigations beyond precision tests of quantum electrodynamics are considered. This revised version was published online in July 2006 with corrections to the Cover Date.     

Quantum beats in hydrogen and antihydrogen atoms in an external electric field

An effect of quantum beats that arises due to the coherent excitation of 2s and 2p states of hydrogen and antihydrogen atoms in an external electric field is described. It is shown that the quantum beat signal contains terms linear in electric field, i.e., is of opposite sign for the hydrogen and antihydrogen atoms. The conditions for the observation of this effect are discussed.     

The Standard Model in strong fields: electroweak radiative corrections for highly charged ions

Electroweak radiative corrections to the matrix element are calculated for highly charged hydrogen like ions. The operator represents the parity nonconserving relativistic effective atomic Hamiltonian at the tree level. The deviation of these calculations from the calculations valid for the neutral atoms demonstrates the effect of the strong field. This revised version was published online in August 2006 with corrections to the Cover Date.     

Hyperfine structure of highly charged 23892U ions with rotationally excited nuclei

The hyperfine structure (hfs) of electron levels of 23892U ions with the nucleus excited in the low-lying rotational 2(+) state with an energy E(2(+)) = 44.91 keV is investigated. In hydrogenlike uranium, the hfs splitting for the 1s(1/2) ground state of the electron constitutes 1.8 eV. The hyperfine-quenched (hfq) lifetime of the 1s2p 3P0 state has been calculated for heliumlike 23892U and was found to be 2 orders of magnitude smaller than for the ion with the nucleus in the ground state. The possibility of a precise determination of the nuclear g(r) factor for the rotational 2(+) state by measurements of the hfq lifetime is discussed.     

Extension of the sum rule for the transition rates between multiplets to the multiphoton case

The sum rule for the transition rates between the components of two multiplets, known for the one-photon transitions, is extended to the multiphoton transitions in hydrogen and hydrogen-like ions. As an example the transitions 3p–2p, 4p–3p and 4d–3d are considered. The numerical results are compared with previous calculations.     

Potential energy curves for excited states of the hydrogen-antihydrogen system

The potential energy curves for the hydrogen-antihydrogen (HH) system in states with a leptonic orbital angular momentum projection Lambda=0, 1, 2, 6, and 30 are presented. Within the framework of the adiabatic picture, explicitly correlated Gaussians are used as basis functions which describe accurately the hydrogen-antihydrogen interaction. The critical internuclear distances where the system transforms into positronium and protonium atoms are found. Adiabatic corrections to the potential energy curves are also estimated.     

Second-order correlation potential in the Kohn–Sham approximation for atoms

A new type of correlation functional derived from the second-order expression for the correlation energy of an atom is proposed. The derived correlation potential contains one free parameter, which is determined by fitting the known pair correlation energy. The calculations with this potential in the Kohn–Sham approximation give rather accurate values for the matrix elements of different operators.