| Abstract: | We present a formal device for calculation of a meson propagator in infinite nuclear matter, through the calculation of the ground state energy of the system in the presence of external, static meson fields, using a pseudo-Hamiltonian simply related to the actual Hamiltonian. This approach is particularly well adapted for dealing with some effects that are not taken into account at all in multiple scattering approaches, for example, the effects of nuclear forces on the intermediate states which are involved in the meson-single-nucleon scattering. A theorem is proved about limiting conditions under which the charged pion propagator is independent of the nuclear forces. These conditions are nearly enough realized in π-nucleus scattering (sufficiently below the energy of the first resonance) so that we can evaluate the corrections perturbatively. The (virtually unknown) two-body force between the 3-3 resonance and nucleons is shown to be of considerable importance in determining the π-meson propagator. |
