Regge cuts and neutral pion electroproduction

A complete FESR-plus-Regge analysis is made of neutral pion photoproduction and electroproduction to understand the Regge cut and its dependence onk ², the square of the virtual photon mass. A SCRAM type of model is essential, but contrary to previous expectations the range of the photon-proton interaction which gives rise to the cut increases with-k ², and is not related to the pointlike, scaling behaviour of deep inelastic scattering, which arises from much simpler parton-model diagrams.