The K+p interaction from 864 to 1585 MeV/c; Cross sections and mass distributions

In this paper we present, for five momenta from 864 to 1585 MeV/c, cross sections for stable final states and for resonance production, and an analysis of the KNπ Dalitz plots including the effects of K ∗ (891) − Δ(1236) interference. We see strong interference at all momenta where the K∗ is present, with the relative phase of the K∗N and KΔ amplitudes remaining constant as a function of momentum. We combine our cross-section results with those from other experiments to study the momentum dependence of the partial cross sections in the region of the 1250 MeV/c peak in the total cross section; we find that the total cross-section curve can be represented as the sum of partial cross-section curves, each one smooth and without a peak corresponding to that in the total cross section. Thus this structure is not due to structure in any single partial cross section, but rather to the sharp rises of the single- and double-pion-production channels at widely separated thresholds. This interpretation is at variance with a conventional resonance interpretation of the observed structure in the total cross section.