Diffraction Dissociation and the 1.40-GeVπNPeak inp−pCollisions

Abstract

The quasidiffraction model of Drell and Hiida is applied in an attempt to understand the 1.40-GeV maximum seen in high-energy, small-angle, inelastic $p-p$ scattering. Reasonable agreement is found in absolute magnitude, and in dependence on the energy and scattering angle, but the correct position and width cannot be fitted quite accurately; several different phenomenological form factors are attempted. It is shown that, at very forward angles, there is a cancellation in dependence on the off-shell pion mass between the pion propagator and a kinematic factor arising from the diffraction scattering. This leads to a suppression of waves with angular momentum $j>\mathrm{}\frac{1}{2}$ for the recoiling system, and might be an explanation for the prominence at very small angles of the 1.40-GeV bump relative to the $d_{13}$ and $f_{15}$ isobars.