Projectile Δ excitations in H1(p,n)Nπ reactions

It has recently been proved from measurements of the spin-transfer coefficients D-xx and D-zz that there is a small but nonvanishing Delta S=0 component sigma(0) in the inclusive p(p,n)N pi differential reaction cross section sigma in the forward direction. It is shown that the dominant part of the measured sigma(0) at forward neutron angles can be explained in terms of the projectile Delta excitation mechanism. An estimate is further made of contributions to sigma(0) from s-wave rescattering processes. It is found that the s-wave rescattering contribution is much smaller than the contribution coming from the projectile Delta excitation mechanism. The addition of an s-wave rescattering contribution to the dominant part, however, improves the fit to the data.