Fermi motion and Pauli exclusion principle effects ind(π±, π± p)nin theΔ-resonance region

Abstract

An ab initio method of taking Fermi motion effects in pion scattering into account combined with proper antisymmetrization of the two nucleon final state in $d({\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}} {\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}, p)n$ shows that the reaction amplitude consists of not only a contribution from pion scattering on a proton, but also pion scattering on a neutron, and that the two amplitudes differ considerably in their $\ensuremath{\pi}\ensuremath{-}N$ c.m. energies. The neutron scattering contribution to the differential cross section exceeds 10% in as many as 51 out of 195 ${\ensuremath{\pi}}^{\ensuremath{-}}$ events recorded in a recent kinematically complete experiment by Hoftiezer et al. in the $\ensuremath{\Delta}$-resonance region. In several kinematical situations the neutron contribution exceeds 100% and could even be as high as \ensuremath{\sim}400%.NUCLEAR REACTIONS $d({\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}, {\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}} p)n$, ab initio method for Fermi motion effects, Pauli principle, effective mass, exchange amplitude.