EXCLUSIVE PRODUCTION OF π+π- PAIRS IN PROTON-PROTON AND PROTON-ANTIPROTON COLLISIONS

Abstract

We report on a detailed investigation of four-body pp → ppπ+π- and [Formula: see text] reactions which constitute an irreducible background to three-body processes pp → ppM, where M is a broad resonance in the π+π- channel, e.g. M = σ, ρ0, f0(980), f2(1275), f0(1500). We include double-diffractive contribution (both pomeron and reggeon exchanges) as well as the pion-pion rescattering contributions. The first process dominates at higher energies and small pion-pion invariant masses while the second becomes important at lower energies and higher pion-pion invariant masses. We compare our results with the experimental data. We make predictions for future experiments at PANDA, RHIC, Tevatron and LHC energies. The two-dimensional distribution in rapidity space of pions (yπ+, yπ-) is particularly interesting. The higher the incident energy, the higher preference for the same-hemisphere emission of pions. The processes considered constitute a sizeable contribution to the total nucleon-nucleon cross section as well as to pion inclusive cross section.