Field theoretic treatment ofπ-nuclear scattering

Abstract

The dynamical assumption that single mesons are emitted or absorbed by nucleons is applied to $\ensuremath{\pi}$-nucleus scattering and leads to a $\ensuremath{\pi}$-nucleus Low equation. With the neglect of multinucleon currents and true meson absorption, the $\ensuremath{\pi}$-nucleus Low equation is shown to be equivalent to a linear equation of the same form as in standard theories except for a striking propagator modification arising from the energy dependence of the driving term. The use of a corresponding linear equation for $\ensuremath{\pi}$-nucleon scattering enables us to derive a field-theoretic multiple-scattering series. It is found that the propagator modification eliminates the Kisslinger singularity, reduces the Lorentz-Lorenz effect and local field corrections. The effect of true meson absorption on $\ensuremath{\pi}$-nucleus elastic scattering is also examined and found to be somewhat important at low (\ensuremath{\sim}50 MeV) energies but negligible (due to strong first-order optical absorption) for energies greater than 100 MeV.NUCLEAR REACTIONS Scattering theory, $\ensuremath{\pi}$-nucleon scattering, $\ensuremath{\pi}\ensuremath{-}^{16}\mathrm{O}$ scattering, $E=50\ensuremath{-}275$ MeV.