Measurements are reported of the differential cross section for the reaction π − +p→ ω +n from threshold to a final-state c.m. momentum P ∗ of 200 MeV /c . The previously reported fall in total cross section σ/P ∗ below about 100 MeV/ c is again seen. The differential cross section remains close to isotropic over the entire range. A paralle experiment on the variation in the elastic differential cross section across the threshold shows evidence of this threshold. The elastic data cover a range of incident moments from 1010 to 1180 MeV/ c in steps of 5 MeV/ c .
CROSS SECTION DEPENDENCE ON FINAL STATE CENTRE OF MASS MOMENTUM.
ANGULAR DISTRIBUTIONS ARE ALMOST ISOTROPIC.
LEGENDRE POLYNOMIAL COEFFICIENTS NORMALIZED SUCH THAT SIG = 4*PI*LEG(L=0).
We present results from a high momentum resolution measurement of the π − p elastic differential cross section near the η production threshold. By analysing the cusp discontinuity in the elastic cross section we deduce the non-spin-flip elastic amplitude and compare it with solutions from phase-shift analyses.
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The recoil proton polarization for γ n → π − p was measured around the third resonance region. Both momentum vectors of the proton and the pion were determined by the magnetic spectrometers. The proton polarization was measured by means of proton-carbon scattering in the polarization analyzer located behind the proton spectrometer. Below 900 MeV incident photon energy, our data are consistent with the other existing experimental data ( θ π ∗ = 90° ) and the predictions of partial-wave analyses. Above 1000 MeV, however, a large discrepancy was observed between our data and the predictions of the partial-wave analyses. The discrepancy stands out as the pion c.m. angle increases. A new partial-wave analysis was made for γ n → π − p including our polarization data, and the accuracy of the experimentally determined electromagnetic coupling constant of the third resonances were greatly improved. In particular, a finite amount of the helicity 3 2 amplitude for the γ n → F 15 (1688) resonance was obtained against the predictions of the quark models, by Copley, Karl and Obryk and by Feynman, Kislinger and Ravendal but in agreement with the relativistic quark models of Sugimoto and Toya, and Kubota and Ohta.
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We present data for the single-pion production final states K 0 π − p, K − π 0 p and K − π + n from K − p interactions at 11 c.m. energies between 1775 and 1957 MeV. Using the K 0 π − p events the branching ratio (K s 0 → π + π − /K s 0 → all) has been determined to be 0.657 ± 0.011. New values have also been determined for the masses and widths of the K ∗0 (890) and the K ∗− (8990). These give a value of 1.5 ± 1.5 MeV for the electromagnetic mass splitting of the K ∗ . Differential cross sections and the spin-density matrix elements have been extracted for the reactions K − p → K ∗− p and K − p → K ∗0 n . An energy dependent partial-wave analysis of the K ∗ N channel from threshold up to 2170 MeV c.m. energy has been carried out yielding values for 17 resonant amplitudes for the expected Y ∗ 's and a new resonance, the S01(2030).
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New data are presented for the reaction K − p → Λπ + π − at 11 energies between 1775 and 1957 MeV in the centre-of-mass. New values for the masses and widths of the Σ ± (1385) are given. The differential cross sections and the complete spin density matrices for the reactions K − p → π ± Σ ∓ (1385) were extracted from these data using also the information from the Λ decay. An energy-dependent partial-wave analysis has been carried out over the c.m. range 1775–2170 MeV also using data from an earlier experiment. Comparisons between the observed resonant amplitudes and SU(3) and SU(6) W ⊎ O(3) predictions have been made.
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LEGENDRE POLYNOMIAL COEFFICIENTS FOR ANGULAR DISTRIBUTION OF CROSS SECTION.
LEGENDRE POLYNOMIAL COEFFICIENTS FOR ANGULAR DISTRIBUTION OF DENSITY MATRIX ELEMENT RHO(MM=33,P=4,XYZ=SH).
n p annihilations with ⩾ 3 prongs with an incident antineutron momentum between 0.5 and 0.8 GeV/ c are analysed. We present the topological branching ratios and cross sections, the resonance production rates and possible ϱ-ω interference effects.
CHANNEL FRACTIONS IN <2PI+ PI- PI0> FINAL STATE.
We present extracted data for the pure I = 1 π 0 Λ (1520) channel from the reaction K − p → K − p π 0 at 11 incident momenta between 0.96 and 1.355 GeV/ c (1775 to 1960 MeV c.m. energy). A partial-wave analysis of this channel has been carried out over a broad c.m. energy range from 1710 to 2170 MeV using data at 27 momenta from this and earlier experiments. The 5 2 − Σ(1775) and built7 2 + Σ(2030) resonances are found to decay strongly to this channel. Amplitudes are also obtained for less dominant and less well-established resonances.
THESE CROSS SECTIONS ARE GIVEN IN TABLE 1B OF W. CAMERON ET AL., NP B146, 327 (1978).
LEGENDRE POLYNOMIAL COEFFICIENTS FOR ANGULAR DISTRIBUTION OF CROSS SECTION.
LEGENDRE POLYNOMIAL COEFFICIENTS FOR ANGULAR DISTRIBUTION OF DENSITY MATRIX ELEMENT RHO(MM=33,XYZ=SH).
We present results for the total cross section of e + e − annihilation into two hadrons at 1.6 GeV: σ ππ = σ KK = (1.8 ± 1.1) × 10 -33 cm 2 .From these values we obtain the time-like electromagnetic form factors these mesons: | F π | 2 = 0.24 ± 0.14 and | F K | 2 = 0.46 ± 0.26.
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The polarization parameter has been measured in K − p elastic scattering at eight incident beam momenta between 650 MeV/ c and 1071 MeV/ c throughout a center of mass angular range of −0.75 < cos θ ∗ < 0.85 . Experimental results and coefficients of Legendre polynomial fits to the data are presented and compared with other measurements and partial wave analysis.
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SINGLE CHARGED PARTICLE MOMENTUM DISTRIBUTION.
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