Small x physics.

Abstract

We study the small-z limit of the structure functions for deep inelastic scattering in Quantum Chromodynamics. The standard approach to this process, based on the DGLAP equations, runs into difficulties in the small-x region due to the higher order corrections becoming large. As an attempt to overcome these obstacles we reinterpret the small-z limit in terms of high energy asymptotics. The relevant high energy formalism is developed in terms of Reggeon Field Theory, which leads to the BFKL equation for the scattering amplitude. These results are reviewed fully, for completeness. We then apply the resulting formalism to structure functions at small-z to determine the phenomenological implications of this high energy resummation. The DESY electron-proton collider HERA is presently exploring the region of the structure functions for x ≤ 10(^-3), Q(^2) ~ 10 GeV(^2) and the results of these experiments are compared with our theoretical analysis. The structure functions are a very inclusive measurement; so in order to try and focus on some cleaner indication of the BFKL behaviour we then turn to an analysis of dijet production in deep inelastic scattering. The results of the BFKL formalism are compared with standard analysis in terms of the DGLAP equations.