Low-lying Electron Energy Levels in Three-Particle Electron-Muon Ions of Li, Be, and B

The electron Lamb shift (2P − 2S) and the energy interval (2S − 1S) in muonelectron ions of lithium, beryllium, and boron have been calculated within the framework of the perturbation theory method for the fine structure constant and the electron-muon mass ratio. The corrections of the first and second orders of the perturbation theory, which include the effects of vacuum polarization, nuclear structure and recoil, are taken into account. The obtained analytical results in perturbation theory are compared with the results of calculations within the framework of the variational approach. The obtained values for the Lamb shift (2P − 2S) and the interval (2S − 1S) can be used for comparison with future experimental data and verification of quantum electrodynamics.