Interpretation of quasielastic pion scattering coincidence experiments

The energy dependence of the $\mathrm{np}$ charge exchange cross section, the angular dependence of the free ${\pi }^{\pm }p$ cross section ratio, and nucleon "absorption" due to quasielastic scattering are significant in predicting (${\pi }^{\pm }$,${\pi }^{\pm }N$) ratios. When these effects are taken into account, recent ($\pi$,$\pi N$) coincidence data can be understood in the impulse approximation picture, with the recoil nucleon subject to charge exchange on leaving the nucleus.