A calculation of the ground-state hyperfine frequency in muonic helium is given. Perturbation theory is applied to the Schrödinger equation to obtain a series in $\frac{m_e}{m_{\mu }}$. The value obtained is 4462.6 ± 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 ${\left(\alpha {\mu }^{-}\right)}^{+}$ nucleus.

• Received 30 May 1979

DOI:https://doi.org/10.1103/PhysRevA.22.1572