Soft gluon radiation and energy dependence of total hadronic cross sections

Abstract

An impact parameter representation for soft gluon radiation is applied to obtain both the initial decrease of the total cross section (σ_tot) for proton-proton collisions as well as the later rise of σ_tot with energy for both pp and pp^- . The nonperturbative soft part of the eikonal includes only limited low energy gluon emission and leads to the initial decrease in the proton-proton cross section. On the other hand, the rapid rise in the hard, perturbative jet part of the eikonal is tamed into the experimentally observed mild increase by soft gluon radiation whose maximum energy rises slowly with energy.