Pion-nucleus optical potential including the nuclear Hamiltonian

We use the fact that the mass of the pion is much smaller than the mass of the nucleon to derive an expression for the first-order pion-nucleus optical potential that includes the effect of the nuclear Hamiltonian through a single-particle model. We apply this potential to calculate the total and reaction cross sections of C12 and the charge-exchange cross section to the isobaric analog state in C13 for energies between 0 and 300 MeV, obtaining qualitative agreement with experiment. NUCLEAR REACTIONS C13(π+,π0), C12(π+,π+), E=0-300 MeV; calculated σtot(E), σreac(E), and σcex(E).