Scaling and duality in electro- and photoproduction

Abstract

Using new sum rules and a new scaling variable we show that scaling holds even for small q 2 and for physical photons. We also discuss local duality in electro production and show that to a good approximation it holds in all directions in the ν − q 2 plane. In particular, we are able to construct the high energy electroproduction structure function curve from photoproduction data, Thus, we present a unified, “scale invariant” picture of photon-nucleon total cross sections that adds to the challenge of determining the origin of scaling.