Considerations concerning diffraction scattering in quantum chromodynamics

Abstract

A model for diffractive, especially elastic hadron-hadron scattering at high c.m. energies squared s and small momentum transfer squared | t| is developed, based on quantum chromodynamics (QCD). First the scattering of hadron constituents, partons, is considered. In this paper we study mainly the scattering of quarks and antiquarks. The s-dependence of the amplitudes is treated by analytical means using a functional integral approach and an eikonal approximation. The t-dependence of the amplitudes is then shown to be governed by a certain correlation function of gluon string operators. A calculation of this function by non-perturbative methods in the framework of lattice OCD or in the stochastic vacuum field model should be feasible. The transition from the parton to the hadron level is accomplished by constructing an effective S-operator in terms of local tensor operators. In this way we avoid dealing explicitly with hadronic wave functions. In our approach the bound state nature of the hadrons enters through matrix elements of the local operators, where information from deep inelastic lepton-hadron scattering exists. The resulting expression for the elastic hadron-hadron scattering amplitude is discussed and is shown to lead to an understanding of various phenomenological findings. The physical picture emerging is one where single partons of the hadrons interact at a time, i.e., the “Pomeron” couples to single partons. This was suggested previously by phenomenological analyses of experiments and by theoretical investigations of an abelian gluon model.