Chapter 4.3.2 - High-Energy Elastic Scattering and Total Cross Section

Abstract

This chapter provides a review of the experimental results on total cross sections and elastic scattering in the energy range explored by the hadron colliders. Hadron collisions at high energy exhibit the typical features of diffraction. At low-momentum transfer the differential cross section of elastic scattering shows a sharp forward peak followed by a dip-bump structure. At these energies many inelastic channels are open and elastic scattering appears to be essentially the “shadow” of the inelastic processes. The wavelength of the wave being scattered is much smaller than the typical dimensions of the scattering system. The diffracted waves then add up coherently in the forward direction, giving rise to a sharp forward peak. Various diffraction models have been constructed with specific assumptions on the impact parameter dependence of the opacity function Ω. Regge theory is able to provide a rather good description of the energy dependence of the total cross sections. Information on the total cross section of protons at very high energies, above those accessible with present accelerators, is provided by the study of the interaction of primary cosmic rays in the atmosphere. The total cross section on nucleons is derived from the measurement of the absorption length in air by means of the Glauber model.