Energy Levels of Three-Particle Muon–Electronic Ions

The muonic 2P–2S Lamb shift in muon–electron atoms and ions of helium, lithium, beryllium, and boron with the electron in the ground state is calculated by perturbation theory in the fine structure constant and the electron–muon mass ratio. The corrections of first and second orders of perturbation theory on the vacuum polarization, nuclear structure, and recoil are taken into account.