Nucleon-Nucleon Diffraction Scattering

A calculation of diffraction effects in nucleon-nucleon collisions is carried out by using the unitarity of the $S$ matrix. In the diffraction approximation, a set of coupled integral equations for the Wolfenstein amplitudes is derived. The inhomogeneous terms are calculated by taking into account the intermediate state with one pion and two nucleons. For the inelastic matrix elements the modified one-pion-exchange expressions have been used. The integral equations are then solved by a numerical iterative procedure; the results are compared with experiments around 1 GeV. The shape of the experimental cross section is reproduced, but evidence is obtained that potential scattering is still important at these energies. A remarkable prediction is the appearance of a backward peak in neutron-proton scattering.