Pion-nucleus scattering at 800 MeV/c

Elastic π${\mathrm{-}}^{12}$C scattering at 800 MeV/c is investigated by the means of the Glauber theory and the optical-potential model. Various effects associated with the first-order potential are carefully examined as well as higher-order effects of nuclear correlations and pion absorption. A clear discrepancy persists between the calculation and the data. The calculation is extended to the single- and double-charge-exchange processes at 800 MeV/c.