(π,πn) puzzle above the (3,3) resonance

We calculate the corrections due to pion production, Fermi motion, and the Pauli principle on the ratio of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({\pi }^{\pm },\pi N){}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ total cross sections for particle-stable final states. These corrections are important above 400 MeV. When they are combined with those estimated earlier for final state nucleon charge exchange interactions, good agreement is obtained with the data, which cover the energy region from 40 to 550 MeV.