Modeling of a Microscopic Optical Pion–Nucleon Potential at Energies in the (3, 3)-Resonance Region and Nuclear-Matter Effect on the Pion–Nucleon Amplitude

摘要

Differential cross sections for elastic pion scattering on a number of nuclei at energies between 130 and 290 MeV are calculated. For this purpose, use is made of a microscopic optical pion–nucleus potential that was obtained on the basis of the Glauber theory of high-energy scattering and which is determined by the density distribution of pointlike target nucleons and by the pion–nucleon scattering amplitude. The calculation of the cross sections in question is based on solving the respective relativistic wave equation. Three parameters of the pion–nucleon amplitude are fitted in performing a comparison with experimental data. These are the total cross section for pion–nucleon scattering, the ratio of the real to the imaginary part of the forward pion–nucleon scattering amplitude, and the slope parameter. The resulting values of these parameters are then compared with their counterparts for scattering on free nucleons. The character of nuclear-matter-induced changes in these parameters is studied.