Measurements of the pd annihilation at rest

The measurement of different reactions of pd annihilation at rest in a gaseous target has been performed using the OBELIX spectrometer at LEAR (CERN). A strong deviation from the OZI-rule prediction was found from the measurement of the ratio R = φπ ωπ in two regions of proton momenta, P < 200 MeV/c and P > 400 MeV/c: R( φπ^- ωπ^-) = (133 ± 26) × 10^-3 and (113 ± 30) × 10^-3, respectively. These values are about 30 times greater than the theoretical prediction. For the first time the excitation of the †-resonance was observed among the final-state products of pd annihilation. The existence of a broad enhancement in the 4π invariant mass at m ≈ 1480 MeV, seen in previous experiments, was confirmed. A ≈ 100 MeV downward shift of the bump position, when the proton momentum increased up to P > 400 MeV/c, was also observed, while the positions of ω, ρ{variant} and f₂(1270) did not change with the proton momentum. The following branching ratios were measured: BR(pd → π^-φp) = (6.62 ± 0.49) × 10^-4, for P < 200 MeV/c; BR(pd → π^-φp) = (0.95 ± 0.22) × 10^-4, for P > 400 MeV/c; BR(pd → π^-ωp) = (49.7 ± 8.9) × 10^-4, for P < 200 MeV/c; BR(pd → π^-ωp) = (8.38 ± 1.09) × 10^-4, for P > 400 MeV/c; BR(pd → 2π^-π⁺p) = (150 ± 6) × 10^-4, for P < 200 MeV/c; BR(pd → 2π^-π⁺p) = (16.6 ± 0.9) × 10^-4, for P > 400 MeV/c; BR(pd → 3π^-2π⁺p) = (326 ± 12) × 10^-4, for P < 200 MeV/c; BR(pd → 3π^-2π⁺p) = (44 ± 7) × 10^-4, for P > 400 MeV/c; BR(pd → ΛK⁺π^-) = (0.96 ± 0.19) × 10^-4, for P > 400 MeV/c; BR(pd → ΛK⁺π^-π⁰) = (3.5 ± 0.8) × 10^-4, for P > 400 MeV/c; BR(pp → 2π^-2π⁺) = (540 ± 20) × 10^-4; BR(pp → 3π^-3π⁺) = (251 ± 21) × 10^-4.