[en] Measurements of two-body branching ratios for pbarp annihilations at rest in liquid and gaseous (12ρ_STP) hydrogen are reported. Channels studied are pbarp→π⁰π⁰,π⁰η, K⁰_SK⁰_L, K⁺K^-. The branching ratio for the π⁰π⁰ channel in liquid H₂ is measured to be (6.14±0.40)x10^-4. The results are compared with those from other experiments. The fraction of P-state annihilation for a range of target densities from 0.002ρ_STP to liquid H₂ is determined. Values obtained include 0.11±0.02 in liquid H₂ and 0.48±0.04 in 12ρ_STP H₂ gas

[en] A fresh analysis is reported of high statistics Crystal Barrel data on pp →3π⁰, ηηπ⁰, ηπ⁰ π⁰ and ηη'π⁰ at rest. This analysis is made fully consistent with CERN-Munich data on π⁺π^- →π⁺π^- up to a mass of 1900 MeV, with GAMS data on π⁺π^- →π⁰ π⁰, and with BNL and ANL data on π⁺π^-→KK, which are fitted simultaneously. There is evidence for an I = 0, J^PC = 2⁺⁺ resonance with weak (≤7%) coupling to ππ, strong coupling to both ρρ and ωω and pole position 1534 - i90 MeV. This resonance agrees qualitatively with GAMS and VES data on ππ→ωω, previously interpreted in terms of a resonance at 1590-1640 MeV. New masses and widths for (A) f₀(1370) and (B) f₀(1500), fitted to all eight data sets, are M_A = 1300 ±15 MeV, Γ_A= 230 ±15 MeV, M_B = 1500 ±8 MeV, Γ_B = 132 ±15 MeV. Branching ratios to ππ and ηη are given, and differ significantly from earlier determinations because of a new procedure. (orig.)

[en] We present a measurement and partial wave analysis of the final state K_LK^±π^minus-plus of bar pp annihilation at rest in liquid hydrogen. This reaction is important for the study of the bar KK decay mode of scalar resonances, in particular, the isovectors a₀(980) and a₀(1450). The determination of the a₀(1450) production also fixes the bar KK coupling of the isoscalar f₀(1500) which is discussed as a glueball. We find B(bar pp→a₀(1450)π;a₀(1450)→ bar KK)=(8.88±1.68)x10^-4 and hence B(bar pp→f₀(1500)π;f₀(1500)→ bar KK)=(4.52±0.36)x10^-4. The mass and width of a₀(1450) are m=1480±30MeV/c² and Γ=265±15MeV/c², respectively. For a₀(980) we determine the relative ratio B(bar pp→a₀π;a₀→ bar KK)/B(bar pp→a₀π;a₀→πη) =0.23±0.05 and its relative coupling, bar KK to πη, is 1.03±0.14. copyright 1998 The American Physical Society