Applicability of the Glauber approximation to nuclear scattering of pions in the energy region of the resonance

The author demonstrates the approximate applicability of the criteria for the Glauber approximation to nuclear scattering of pions in the energy region of the resonance. It is shown that the approximation should give a reasonable fit to pion scattering from nuclei in the energy region of the (3,3) resonance, in spite of the strong p-wave interaction between pions and nucleons. Nuclear binding effects on the target nucleons, play an important role in making the Glauber approximation valid with a reasonable accuracy. A new formulation of the pion-nucleon scattering amplitude as modified by the effect of nuclear binding on the target nucleon is proposed. The nuclear binding effects confine target nuclei into low-lying states in intermediate states. The locality of the T-matrix for nuclear scattering, which is essential in the Glauber approximation, is shown not to be violated by this freezing of nuclei. (21 refs)