Reactions with six charged final state particles produced in π-p interactions at 13.1 GeV/c

Results are presented from a study of 39863 six-prong events produced in π+p interactions at 13.1 GeV/c incident momentum. The cross sections are determined to be 4.6 +- 0.1 mb for all six-prong events, 0.32 +- 0.01 mb for π+p → p3π+2π-, and 0.55 +- 0.22 for π+p → p3π+2π-π0. The latter two cross sections are compared with those at other momenta by removing phase space effects. By similarly studying 20 other π+-p reactions, correlations between the cross section dependences and dominant exchange particles are observed. Resonance production is found to be strong, with Δ++, rho0, and f0 produced in the p3π+2π- channel and Δ++, rho0, rho+, ω, eta, and eta' produced in the p3π+2π-π0 channel. Fitted masses, widths, and cross sections are given. The branching ratio (f0 → 2π+2π-)/(f0 → π+π-) is determined to be 8.6 +- 2.1 percent. A semi-inclusive analysis is presented in terms of the Feynman x variable using eight π+p reactions for the particles π+, π-, proton, and π0. Correlations between the distribution shapes and dominate features of the mechanisms are seen. Three models are applied to the p3π+2π- channel. The phase space model, based on experimentally determined amounts of resonance production and phase space, displays strong deviations when compared with experimental distributions. The F(t) model, utilizing in addition the experimental proton-proton momentum transfer, is a distinct improvement, but still reproduces the experimental data poorly. The ABFST model, based on factorization of the cross section into off-shell elastic scatters and pion exchanges, fails to correctly describe the cross section dependence, but successfully reproduces nearly all dynamic features of the reaction at 13.1 GeV/c