Pion-nucleus elastic scattering at intermediate energies

Dynamical modifications of the pion-nucleus optical potential due to binding effects on the target nucleons are calculated for pions of energies in the range 120--600 MeV. Calculations are performed using an independent particle model for the nucleus; however, a prescription for incorporation of the Pauli pinciple is given and its effects are studied. Resulting corrections to the potential are of the order of 50--100% near (3,3) resonance and fall to negligible values at energies less than 120 MeV and greater than 450 MeV. Our correction is such as to increase the nuclear opacity. Pion-nucleus total cross sections and angular distributions are modified by binding effects by 10--20%. Comparison with π-12C total cross section data section shows that our theory reproduces well the energy dependence of the correction required to reconcile theory and experiment, and produces about 50% of the necessary increase in the magnitude of the theoretical cross section