Analysis of experimental data on the pion scattering on nuclei within the microscopic optical potential and in-medium effect on the pion-nucleon amplitude of scattering

Abstract

Analysis is performed of calculations of the elastic scattering differential cross sections of pions on the 28 Si, 40 Ca, 58 Ni and 208 Pb nuclei at energies from 130 to 290 MeV basing on the microscopic optical potential (OP) constructed as an optical limit of a Glauber theory. Such an OP is defined by the corresponding target nucleus density distribution and by the pion-nucleon πN amplitude of scattering. The pion-nucleus cross sections are calculated by numerical solving the corresponding relativistic wave equation. The three (say, "in-medium") parameters of the πN amplitude, the total cross section, the ratio of real to imaginary part of the forward πN amplitude, and the slope parameter, were obtained by fitting the calculated cross sections to the respective experimental data. A difference is discussed between the best-fit "in-medium" parameters and the "free" parameters of the πN scattering amplitudes known from the experimental data on scattering of pions on free nucleons.