Pion-nucleon partial-wave analysis

Abstract

We have carried out a partial-wave analysis of amalgamated pion-nucleon scattering data at 35 momenta in the range 0.429-1.995 GeV/c. At each momentum, a large set of fits was obtained, with the amplitude represented as the sum of a fixed background and the fitted terms of an accelerated convergence expansion. The effects of discrete and continuum ambiguities were separated by special statistical and numerical techniques which sort the fits into clusters. Dispersion relations on selected curves within the kinematical region for physical scattering were used to resolve the ambiguities and to derive constraints. These constraints, which ensure that the fitted amplitudes have a relatively smooth energy dependence consistent with analyticity, were used iteratively to arrive at a unique set of amplitudes which fit the scattering data throughout the energy region studied.