Access to the Kaon Radius with Kaonic Atoms

We put forward a method for determination of the kaon radius from the spectra of kaonic atoms. We analyze the few lowest transitions and their sensitivity to the size of the kaon for ions in the nuclear charge range Z = 1 - 100, taking into account finite-nuclear-size, finite-kaon-size, recoil and leading-order quantum-electrodynamic effects. Additionally, the opportunities of extracting the kaon mass and nuclear radii are demonstrated by examining the sensitivity of the transition energies in kaonic atoms

Self-energy correction to the energy levels of heavy muonic atoms

The first fully relativistic, rigorous QED calculations of the self-energycorrection to the fine-structure levels of heavy muonic atoms are reported. Wediscuss nuclear model and parameter dependence for this contribution as well asnumerical convergence issues. The presented results show sizable disagreementwith previously reported estimations, including ones used for the determinationof the nuclear root-mean-square radii, and underline the importance of rigorousQED calculations for the theoretical prediction of the spectra of muonic atoms.<br

X-ray fluorescence spectrum of highly charged Fe ions driven by strong free-electron-laser fields

The influence of nonlinear dynamical effects is analyzed on the observed spectra of controversial 3C and 3D astrophysically relevant x-ray lines in neonlike Fe${}^{16+}$ and the A, B, C lines in natriumlike Fe${}^{15+}$ ions. First, a large-scale configuration-interaction calculation of oscillator strengths is performed with the inclusion of higher-order electron-correlation effects. Also, quantum-electrodynamic corrections to the transition energies are calculated. Further considered dynamical effects provide a possible resolution of the discrepancy between theory and experiment found by recent x-ray free-electron-laser measurements of these controversial lines. We find that, for strong x-ray sources, the modeling of the spectral lines by a peak with an area proportional to the oscillator strength is not sufficient and nonlinear dynamical effects have to be taken into account. Thus, we advocate the use of light-matter-interaction models also valid for strong light fields in the analysis and interpretation of the associated astrophysical and laboratory spectra. We investigate line-strength ratios distinguishing between the coherent and incoherent parts of the emission spectrum. In addition, the spectrum of Fe${}^{15+}$, an autoionizing ion which was also present in the recent laboratory experiment, is also analized

Access to improve the muon mass and magnetic moment anomaly via the bound-muon gg factor

A theoretical description of the $g$ factor of a muon bound in a nuclear potential is presented. One-loop self-energy and multi-loop vacuum polarization corrections are calculated, taking into account the interaction with the binding potential exactly. Nuclear effects on the bound-muon $g$ factor are also evaluated. We put forward the measurement of the bound-muon $g$ factor via the continuous Stern-Gerlach effect as an independent means to determine the free muons magnetic moment anomaly and mass. The scheme presented enables to increase the accuracy of the mass by more than an order of magnitude

Testing standard-model extensions with isotope shifts in few-electron ions

When collecting spectroscopic data on at least four isotopes, nonlinearitiesin the King plot are a possible sign of Physics beyond the Standard Model. Inthis work, an improved approach to the search for hypothetical new interactionswith isotope shift spectroscopy of few-electron ions is presented. Very carefulaccount is taken of the small nuclear corrections to the energy levels and thegyromagnetic factors, which cause deviations from King linearity within theStandard Model and are hence a possible source of confounds. In this newapproach, the experimental King nonlinearity is not compared to the vanishingprediction of the Standard Model at the leading order, but to the calculatedfull Standard Model contribution to King nonlinearity. This makes searching forbeyond-the-Standard-Model physics with King linearity analysis possible in avery-high-precision experimental regime, avoiding confounds. The bounds whichcan be set on beyond-the-Standard-Model parameters remain limited by theuncertainties on the small Standard Model nuclear corrections which cause Kingnonlinearity. Direct comparison between theory and experiment on a single pairof isotopes is advocated as a more suitable approach for few-electron ions.<br

Ground-state hyperfine structure of H-, Li-, and B-like ions in middle-Z region

The hyperfine splitting of the ground state of H-, Li-, and B-like ions is investigated in details within the range of nuclear numbers Z = 7-28. The rigorous QED approach together with the large-scale configuration-interaction Dirac-Fock-Sturm method are employed for the evaluation of the interelectronic-interaction contributions of first and higher orders in 1/Z. The screened QED corrections are evaluated to all orders in (\alpha Z) utilizing an effective potential approach. The influence of nuclear magnetization distribution is taken into account within the single-particle nuclear model. The specific differences between the hyperfine-structure level shifts of H- and Li-like ions, where the uncertainties associated with the nuclear structure corrections are significantly reduced, are also calculated.Comment: 22 pages, 11 tables, 2 figure

Relativistic effective charge model of a multi-electron atom

A relativistic version of the effective charge model for computation of observable characteristics of multi-electron atoms and ions is developed. A complete and orthogonal Dirac hydrogen basis set, depending on one parameter -- effective nuclear charge $Z^{*}$ -- identical for all single-electron wave functions of a given atom or ion, is employed for the construction of the secondary-quantized representation. The effective charge is uniquely determined by the charge of the nucleus and a set of electron occupation numbers for a given state. We thoroughly study the accuracy of the leading-order approximation for the total binding energy and demonstrate that it is independent of the number of electrons of a multi-electron atom. In addition, it is shown that the fully analytical leading-order approximation is especially suited for the description of highly charged ions since our wave functions are almost coincident with the Dirac-Hartree-Fock ones for the complete spectrum. Finally, we evaluate various atomic characteristics, such as scattering factors and photoionization cross-sections, and thus envisage that the effective charge model can replace other models of comparable complexity, such as the Thomas-Fermi-Dirac model for all applications where it is still utilized

QED calculation of the 2p1/2-2s and 2p3/2-2s transition energies and the ground-state hyperfine splitting in lithiumlike scandium

We present the most accurate up-to-date theoretical values of the {2p_{1/2}}-{2s} and {2p_{3/2}}-{2s} transition energies and the ground-state hyperfine splitting in ${\rm Sc}^{18+}$. All two- and three-electron contributions to the energy values up to the two-photon level are treated in the framework of bound-state QED without \aZ-expansion. The interelectronic interaction beyond the two-photon level is taken into account by means of the large-scale configuration-interaction Dirac-Fock-Sturm (CI-DFS) method. The relativistic recoil correction is calculated with many-electron wave functions in order to take into account the electron-correlation effect. The accuracy of the transition energy values is improved by a factor of five compared to the previous calculations. The CI-DFS calculation of interelectronic-interaction effects and the evaluation of the QED correction in an effective screening potential provide significant improvement for the $2s$ hyperfine splitting. The results obtained are in a good agreement with recently published experimental data.Comment: 10 pages, 2 table

Theory of the two-loop self-energy correction to the g factor in nonperturbative Coulomb fields

Two-loop self-energy corrections to the bound-electron $g$ factor are investigated theoretically to all orders in the nuclear binding strength parameter $Z\alpha$. The separation of divergences is performed by dimensional regularization, and the contributing diagrams are regrouped into specific categories to yield finite results. We evaluate numerically the loop-after-loop terms, and the remaining diagrams by treating the Coulomb interaction in the electron propagators up to first order. The results show that such two-loop terms are mandatory to take into account for projected near-future stringent tests of quantum electrodynamics and for the determination of fundamental constants through the $g$ factor

Evidence Against Nuclear Polarization as Source of Fine-Structure Anomalies in Muonic Atoms

A long-standing problem of fine-structure anomalies in muonic atoms is revisited by considering the $\Delta 2p$ splitting in muonic $^{90}\mathrm{Zr}$, $^{120}\mathrm{Sn}$ and $^{208}\mathrm{Pb}$ and the $\Delta 3p$ splitting in muonic $^{208}\mathrm{Pb}$. State-of-the-art techniques from both nuclear and atomic physics are brought together in order to perform the most comprehensive to date calculations of nuclear-polarization energy shifts. Barring the more subtle case of muonic $^{208}\mathrm{Pb}$, the results suggest that the dominant calculation uncertainty is much smaller than the persisting discrepancies between theory and experiment. We conclude that the resolution to the anomalies is likely to be rooted in refined QED corrections or even some other previously unaccounted-for contributions