Event Structure and Resonance Production in Exclusive Antiproton-Proton Annihilations at 8.3 and 13.0 Gev/c.

A high statistics study of the exclusive annihilation reactions pp (--->) 2(pi)('+)2(pi)('-), 2(pi)('+)2(pi)(' -)(pi)('0), 3(pi)('+)3(pi)('-), and 3(pi)('+)3(pi)('-)(pi)('0) at antiproton beam momenta of 8.3 and 13.0 GeV/c is reported. The data presented is from an experiment performed at the Stanford Linear Accelerator Center using the Large Aperture Solenoid Spectrometer (LASS). Reaction cross sections are measured and event shapes are analyzed at both beam momenta. For the 8.3 GeV/c data samples, charged pion momentum distributions are presented and the (pi)('-)/(pi)('+) asymmetry is examined as a function of longitudinal momentum. Production rates and momentum distributions for the resonance state (rho)('0)(770 MeV/c('2)), (rho)('(+OR-))(770 MeV/c('2)), (omega)('0)(783 MeV/c('2)), and f('0)(1270 MeV/c('2)) are also investigated. A search is performed for a resonance near 1700 MeV/c('2) decaying into two (rho)('0) mesons. Upper limits are calculated for the production cross section times the branching ratio of this resonance in the 3(pi)('+)3(pi)('-)(pi)('0) final state at 8.3 GeV/c.