No Arabic abstract
QED corrections to the $g$ factor of Li-like and B-like ions in a wide range of nuclear charges are presented. Many-electron contributions as well as radiative effects on the one-loop level are calculated. Contributions resulting from the interelectronic interaction, the self-energy effect, and most of the terms of the vacuum-polarization effect are evaluated to all orders in the nuclear coupling strength $Zalpha$. Uncertainties resulting from nuclear size effects, numerical computations, and uncalculated effects are discussed.
Calculations of various corrections to the g factor of Li-like ions are presented, which result in a significant improvement of the theoretical accuracy in the region Z = 6-92. The configuration-interaction Dirac-Fock method is employed for the evaluation of the interelectronic-interaction correction of order 1/Z^2 and higher. This correction is combined with the 1/Z interelectronic-interaction term derived within a rigorous QED approach. The one-electron QED corrections of first in alpha are calculated to all orders in the parameter alpha Z. The screening of QED corrections is taken into account to the leading orders in alpha Z and 1/Z.
We report calculations of QED corrections to the $g$ factor of Li-like ions induced by the exchange of two virtual photons between the electrons. The calculations are performed within QED theory to all orders in the nuclear binding strength parameter $Zalpha$, where $Z$ is the nuclear charge number and $alpha$ is the fine-structure constant. In the region of low nuclear charges we compare results from three different methods: QED, relativistic many-body perturbation theory, and nonrelativistic QED. All three methods are shown to yield consistent results. With our calculations we improve the accuracy of the theoretical predictions of the $g$ factor of the ground state of Li-like carbon and oxygen by about an order of magnitude. Our theoretical results agree with those from previous calculations but differ by 3-4 standard deviations from the experimental results available for silicon and calcium.
The nuclear recoil effect on the $g$ factor of Li-like ions is evaluated. The one-electron recoil contribution is treated within the framework of the rigorous QED approach to first order in the electron-to-nucleus mass ratio $m/M$ and to all orders in the parameter $alpha Z$. These calculations are performed in a range $Z=3-92$. The two-electron recoil term is calculated for low- and middle-$Z$ ions within the Breit approximation using a four-component approach. The results for the two-electron recoil part obtained in the paper strongly disagree with the previous calculations performed using an effective two-component Hamiltonian. The obtained value for the recoil effect is used to calculate the isotope shift of the $g$ factor of Li-like $^{A}$Ca$^{17+}$ with $A=40$ and $A=48$ which was recently measured. It is found that the new theoretical value for the isotope shift is closer to the experimental one than the previously obtained value.
We report an investigation of the self-energy screening effects for the $g$ factor of the ground state of Li-like ions. The leading screening contribution of the relative order $1/Z$ is calculated to all orders in the binding nuclear strength parameter $Zalpha$ (where $Z$ is the nuclear charge number and $alpha$ is the fine-structure constant). We also extend the known results for the $Zalpha$ expansion of the QED screening correction by deriving the leading logarithmic contribution of order $alpha^5lnalpha$ and obtaining approximate results for the $alpha^5$ and $alpha^6$ contributions. The comparison of the two approaches yields a stringent check of consistency of the two calculations and allows us to obtain improved estimations of the higher-order screening effects.
We investigate electron-correlation effects in the $g$-factor of the ground state of Li-like ions. Our calculations are performed within the nonrelativistic quantum electrodynamics (NRQED) expansion up to two leading orders in the fine-structure constant $alpha$, $alpha^2$ and $alpha^3$. The dependence of the NRQED results on the nuclear charge number $Z$ is studied and the individual $1/Z$-expansion contributions are identified. Combining the obtained data with the results of the all-order (in $Zalpha$) calculations performed within the $1/Z$ expansion, we derive the unified theoretical predictions for the $g$-factor of light Li-like ions.