Excitation of Giant Resonances in Pion Charge Exchange and the Proton-Neutron Density Distributions in Nuclei

Abstract

It is argued that the recently measured (${\ensuremath{\pi}}^{\ensuremath{-}}, {\ensuremath{\pi}}^{0}$) and (${\ensuremath{\pi}}^{+}, {\ensuremath{\pi}}^{0}$) reactions on $^{40}\mathrm{Ca}$ exciting the two components of the giant dipole provide new information about the density distribution of protons and neutrons. The large difference in the (${\ensuremath{\pi}}^{\ensuremath{-}}, {\ensuremath{\pi}}^{0}$) and (${\ensuremath{\pi}}^{+}, {\ensuremath{\pi}}^{0}$) cross sections is mainly due to the effect of Coulomb polarization in the nucleus.