ENERGY LEVELS AND WAVE FUNCTIONS OF PIONIC ATOMS.

Abstract Present data on strong interaction shifts and widths in pionic atoms are analyzed in terms of a non-local effective potential with five parameters. Realistic mass and charge distributions are used and strong interaction effects on the vacuum polarization are included. The dependence of predictions on parameters is discussed; properties of the wave functions are presented for different assumptions of the interaction. The effective potential predicts a change of the attractive p-wave interaction to a repulsion in the region Z ≈ 36. It also suggests important isospin effects in the gradient interaction for very heavy nuclei. The Born approximation of the real isovector part of the potential is in agreement with soft pion theory; this term, as well as the entire real potential, is also close to multiple scattering theory. The analysis suggests that the isoscalar πN amplitude is −0.01 μ −1 ⪅ a N (+) ⪅ 0. The absorptive potential is about a factor of two stronger than predicted.

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