Hyperfine structure in muonic helium

Abstract

A calculation of the ground-state hyperfine frequency in muonic helium is given. Perturbation theory is applied to the Schr\"odinger equation to obtain a series in $\frac{{m}_{e}}{{m}_{\ensuremath{\mu}}}$. The value obtained is 4462.6 \ifmmode\pm\else\textpm\fi{} 3 MHz, which is consistent with experiments at the Swiss Institute for Nuclear Research and the Los Alamos Meson Physics Facility. The theoretical value includes a --- 46-MHz contribution from excited states of the effective ${(\ensuremath{\alpha}{\ensuremath{\mu}}^{\ensuremath{-}})}^{+}$ nucleus.