Investigationof the np → npπ+π– Reaction at Momenta P0 > 3 GeV/c

Abstract

The \(np \to np{{\pi }^{ + }}{{\pi }^{ - }}\) reaction is investigated at the incident neutron momenta \({{P}_{0}}\) = 3.83 and 5.20 GeV/c. Contributions of different diagrams to the reaction cross section are calculated at the momenta from the threshold to 12 GeV/c. It is shown that the main contributions to the \(np \to np{{\pi }^{ + }}{{\pi }^{ - }}\) reaction at momenta above \({{P}_{0}}\) > 3 GeV/c come from diagrams of the reggeized \(\pi \)-meson exchange model (OPER).To study spin effects, the reaction \(np \to np{{\Delta }^{{ + + }}}{{\Delta }^{ - }}\) was separated. It is shown that description of the spin density matrix [\({{\rho }_{{ij}}}\)] requires taking into account the ρ-meson exchange diagram. The reaction \(np \to np{{\rho }^{0}}\) is separated by background subtraction method. The investigation has shown that \({{\rho }^{0}}\)-meson production is described by suspended diagrams of the OPER model.