Hadronic diffractive cross sections and the rise of the total cross section.

Abstract

A model for high-energy hadronic cross sections is proposed. It is based on Regge theory and perturbative QCD, and includes soft and hard mechanisms as well as diffractive processes. The validity range of Regge-pole theory in the description of total, elastic, single-, and double-diffractive cross sections is investigated and inconsistencies found already at CERN LHC and/or SSC energies. Examining unitarity constraints, modifications of the cross section formulas are proposed which allow a continued use of formulas in the Regge spirit to describe elastic and diffractive events. The nondiffractive cross section is allowed to rise at a rate consistent with unitarization of multiple parton-parton scatterings. However, in our picture, the rise of the total cross section with increasing energy is only partly due to the minijet cross sections; the diffractive topologies rise as well. Fully differential distributions are given and convenient parametrizations derived for the integrated rates of elastic and diffractive events. Predictions for the various partial cross sections at Fermilab Tevatron, LHC, and SSC energies are given and compared to other estimates.