Evaluation of the two-photon exchange diagrams for the (1s)22p3/2(1s)^2 2p_{3/2} electron configuration in Li-like ions

We present ab initio calculations of the complete gauge-invariant set of two-photon exchange graphs for the $(1s)^2 2p_{3/2}$ electron configuration in Li-like ions. These calculations are an important step towards the precise theoretical determination of the $2p_{3/2}$-$2s$ transition energy in the framework of QED.Comment: 17 pages, 6 figure

Two-electron self-energy contribution to the ground state energy of heliumlike ions

The two-electron self-energy contribution to the ground state energy of heliumlike ions is calculated both for a point nucleus and an extended nucleus in a wide interval of Z. All the two-electron contributions are compiled to obtain most accurate values for the two-electron part of the ground state energy of heliumlike ions in the range Z=20-100. The theoretical value of the ground state energy of heliumlike uranium, based on currently available theory, is evaluated to be -261382.9(8) eV, without higher order one-electron QED corrections.Comment: 12 pages, 1 figure, LATE

Improved theoretical prediction for the 2s hyperfine interval in helium ion

We consider the uncertainty of theoretical calculations for a specific difference of the hyperfine intervals in the 1s and 2s states in a light hydrogen-like atom. For a number of crucial radiative corrections the result for hydrogen atom and helium ion appears as an extrapolation of the numerical data from medium to low Z. An approach to a plausible estimation of the uncertainty is suggested using the example of the difference $D_{21}= 8E_{hfs}(2s)-E_{hfs}(1s)$

Two-Loop Effects and Current Status of the 4He+ Lamb Shift

We report on recent progress in the treatment of two-loop binding corrections to the Lamb shift, with a special emphasis on S and P states. We use these and other results in order to infer an updated theoretical value of the Lamb shift in 4He+.Comment: 11 pages, nrc1 style; paper presented at PSAS (2006), Venic

QED Effects in Heavy Few-Electron Ions

Accurate calculations of the binding energies, the hyperfine splitting, the bound-electron g-factor, and the parity nonconservation effects in heavy few-electron ions are considered. The calculations include the relativistic, quantum electrodynamic (QED), electron-correlation, and nuclear effects. The theoretical results are compared with available experimental data. A special attention is focused on tests of QED in a strong Coulomb field.Comment: 28 pages, 6 tables, 5 figure

Recoil correction to the ground state energy of hydrogenlike atoms

The recoil correction to the ground state energy of hydrogenlike atoms is calculated to all orders in \alpha Z in the range Z = 1-110. The nuclear size corrections to the recoil effect are partially taken into account. In the case of hydrogen, the relativistic recoil correction beyond the Salpeter contribution and the nonrelativistic nuclear size correction to the recoil effect, amounts to -7.2(2) kHz. The total recoil correction to the ground state energy in hydrogenlike uranium (^{238}U^{91+}) constitutes 0.46 eV.Comment: 16 pages, 1 figure (eps), Latex, submitted to Phys.Rev.

Precision Spectroscopy at Heavy Ion Ring Accelerator SIS300

Unique spectroscopic possibilities open up if a laser beam interacts with relativistic lithium-like ions stored in the heavy ion ring accelerator SIS300 at the future Facility for Antiproton and Ion Research FAIR in Darmstadt, Germany. At a relativistic factor gamma = 36 the 2P 1/2 level can be excited from the 2S 1/2 ground state for any element with frequency doubled dye-lasers in collinear geometry. Precise transition energy measurements can be performed if the fluorescence photons, boosted in forward direction into the X-ray region, are energetically analyzed with a single crystal monochromator. The hyperfine structure can be investigated at the 2P 1/2 - 2S 1/2 transition for all elements and at the 2P 3/2 - 2S 1/2 transition for elements with Z < 50. Isotope shifts and nuclear moments can be measured with unprecedented precision, in principle even for only a few stored radioactive species with known nuclear spin. A superior relative line width in the order of 5E-7 may be feasible after laser cooling, and even polarized external beams may be prepared by optical pumping

Relativistic nuclear recoil corrections to the energy levels of hydrogen-like and high ZZ lithium like atoms in all orders in αZ\alpha Z

The relativistic nuclear recoil corrections to the energy levels of low-laying states of hydrogen-like and high $Z$ lithium-like atoms in all orders in $\alpha Z$ are calculated. The calculations are carried out using the B-spline method for the Dirac equation. For low $Z$ the results of the calculation are in good agreement with the $\alpha Z$ -expansion results. It is found that the nuclear recoil contribution, additional to the Salpeter's one, to the Lamb shift ($n=2$) of hydrogen is $-1.32(6)\,kHz$. The total nuclear recoil correction to the energy of the $(1s)^{2}2p_{\frac{1}{2}}-(1s)^{2}2s$ transition in lithium-like uranium constitutes $-0.07\,eV$ and is largely made up of QED contributions.Comment: 19 pages, latex, accepted for publication in Phys. Rev.

Radiative and interelectronic-interaction corrections to the hyperfine splitting in highly charged B-like ions

The ground-state hyperfine splitting values of high-Z boronlike ions are calculated. Calculation of the interelectronic-interaction contribution is based on a combination of the 1/Z perturbation theory and the large-scale configuration-interaction Dirac-Fock-Sturm method. The screened QED corrections are evaluated utilizing an effective screening potential approach. Total hyperfine splitting energies are presented for several B-like ions of particular interest: {}^{45}Sc{}^{16+}, {}^{57}Fe{}^{21+}, {}^{207}Pb{}^{77+}, and {}^{209}Bi{}^{78+}. For lead and bismuth the experimental values of the 1s hyperfine splitting are employed to improve significantly the theoretical results by reducing the uncertainty due to the nuclear effects.Comment: 12 pages, 2 figures, 3 table

Two-time Green function method in quantum electrodynamics of high-Z few-electron atoms

The two-time Green function method in quantum electrodynamics of high-Z few-electron atoms is described in detail. This method provides a simple procedure for deriving formulas for the energy shift of a single level and for the energies and wave functions of degenerate and quasi-degenerate states. It also allows one to derive formulas for the transition and scattering amplitudes. Application of the method to resonance scattering processes yields a systematic theory for the spectral line shape. The practical ability of the method is demonstrated by deriving formulas for the QED and interelectronic-interaction corrections to energy levels and transition and scattering amplitudes in one-, two-, and three-electron atoms. Numerical calculations of the Lamb shift, the hyperfine splitting, the bound-electron g factor, and the radiative recombination cross section in heavy ions are also reviewed.Comment: 92 pages, 39 figures, 7 table