Hard scattering factorization and light cone hamiltonian approach to diffractive processes

TL;DR

This paper models diffractive deep inelastic scattering using a light cone Hamiltonian approach, linking perturbative and nonperturbative physics to explain experimental data from HERA.

Contribution

It introduces a Hamiltonian formulation emphasizing spacetime aspects of diffraction and explores the role of semihard physics in diffractive parton distributions.

Findings

Diffractive parton distributions can be studied perturbatively for small systems.

For large systems, diffractive distributions are influenced by nonperturbative semihard physics.

The model explains the flat beta behavior and Q^2 dependence observed in HERA data.

Abstract

We describe diffractive deeply inelastic scattering in terms of diffractive parton distributions. We investigate these distributions in a hamiltonian formulation that emphasizes the spacetime picture of diffraction scattering. For hadronic systems with small transverse size, diffraction occurs predominantly at short distances and the diffractive parton distributions can be studied by perturbative methods. For realistic, large-size systems we discuss the possibility that diffractive parton distributions are controlled essentially by semihard physics at a scale of nonperturbative origin of the order of a GeV. We find that this possibility accounts for two important qualitative aspects of the diffractive data from HERA: the flat behavior in beta and the delay in the fall-off with Q^2.