Crossover and Polarization Phenomena in High-Energy Scattering. Cuts, Conspiracies, and Secondary Regge Poles

The usual interpretation, in Regge-pole models, of the change in signs of the cross section differences dσ(ĀB)dt-dσ(AB)dt at t~-0.15 (GeV/c)² observed in elastic πN, KN, and NN scattering is inconsistent with recent data on the reaction γp→π⁰p. It is pointed out that this contradiction is direct evidence for the existence of contributions to the high-energy scattering amplitudes in addition to those of the leading Regge poles. Alternative explanations of the crossover phenomena which avoid the foregoing difficulty are proposed, and their implications are discussed.