Testing atomic wave functions in the nuclear vicinity: The hyperfine structure with empirically deduced nuclear and quantum electrodynamic effects

Calculations of the magnetic hyperfine structure rely on the input of nuclear properties—nuclear magnetic moments and nuclear magnetization distributions—as well as quantum electrodynamic radiative corrections for high-accuracy evaluation in heavy atoms. The uncertainties associated with assumed values of these properties limit the accuracy of hyperfine calculations. For example, for the heavy alkali-metal atoms Cs and Fr, these uncertainties may amount collectively to almost 1% or 2%, respectively. In this paper, we propose a method for removing the dependence of hyperfine structure calculations on assumed values of nuclear magnetic moments and nuclear magnetization distributions by determining these effects empirically from measurements of the hyperfine structure for high states. The method is valid for $s$, $p_{1/2}$, and $p_{3/2}$ states of alkali-metal atoms and alkali-metal-like ions. We have shown that for $s$ states, the dependence on QED effects may also be removed to high accuracy. The ability to probe the electronic wave functions, through hyperfine comparisons, with significantly increased accuracy is important for the analysis of atomic parity violation measurements, and it may enable the accuracy of atomic parity violation calculations to be improved. More broadly, it paves the way for further development of high-precision atomic many-body methods.

Figure 1

Relative correlation corrections $F^{\mathrm{\Sigma }}$ to the hyperfine structure (in $\%$) for Cs, ${\mathrm{Ba}}^{+}$, Fr, and ${\mathrm{Ra}}^{+}$. This corresponds to evaluation of $\langle {\phi }_{\mathrm{Br}}|h_{\mathrm{hfs}}+\delta V_{\mathrm{hfs}}|{\phi }_{\mathrm{Br}}\rangle -\langle \phi |h_{\mathrm{hfs}}+\delta V_{\mathrm{hfs}}|\phi \rangle$ relative to $\langle \phi |h_{\mathrm{hfs}}+\delta V_{\mathrm{hfs}}|\phi \rangle$.