Evidence for Δ− components in nuclei

Abstract

Ratios of double-differential cross sections for incident 500-MeV pions are presented for (π+,π+p) and (π+,π−p) reactions on 12,13C, 90Zr, and 208Pb. A comparison with intra-nuclear cascade-model calculations suggest that the outgoing pion spectra show a feature consistent with quasi-free scattering from the Δ− component of the nuclear ground state wave function.