Energy Level Displacements in Pi-Mesonic Atoms

The energy level shifts and level widths of the $s$ states of the $\pi$-mesonic atoms are discussed. The discussion is limited to fairly light nuclei. On the basis of Orear's determination of the scattering lengths for meson-nucleon scattering, semiquantitative predictions are made. It is pointed out that even a knowledge of the algebraic sign of the level shift would be of value.