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The depolarization parameter Donon in p p elastic scattering has been measured at LEAR for thirteen momenta between 679 and 1550 MeV/c in the backward angular region. Striking disagreement with theoretical models is observed.

New data from SIN and LAMPF improve substantially the determination of NN → πd amplitudes. Data of the Geneva group on spin transfer from proton to deuteron it11 and t22 polarisations determine magnitudes and phases of two amplitudes previously poorly known, namely a5 (3F2) and a7 (1D2→lπ = 3), up to 580 MeV. Three new sets of LAMPF data determine a7 and the magnitude of a5 up to 800 MeV and a8 (1G4), a9 (3F3 → lπ = 4) and a10 (3F4) at 800 MeV. The a7 amplitude is qualitatively more plausible than earlier values; a5, a8, a9 and a10 agree with expectation. The determination of amplitudes is now essentially complete except for the phase of a5 above 580 MeV.

Two high statistics measurements of antiproton-proton small-angle elastic scattering, at p = 233 MeV/c and p = 272 MeV/c, are presented. The measurements were carried out at the LEAR facility at CERN. By the Coulomb-nuclear interference method, values are obtained for the real-to-imaginary ratio ρ of the pp forward nuclear scattering amplitude and for its exponential slope b: ρ = + 0.041 ± 0.026 and b = 71.5 ± 4.5 (GeV/c)−2 at 233 MeV/c and ρ = −0.014 ± 0.027 and b = 47.7 ± 2.7 (GeV/c)−2 at 272 MeV/c. The method to derive these values is discussed in detail and so are the uncertainties contributing to their systematic error. The results are compared with predictions from forward dispersion relation calculations and with predictions from pp potential models.

Analysing power and differential cross-section have been measured for the reactions p p →π − π + , p p →K − K + by the SING Collaboration (PS172) at LEAR, using a polarized target. Preliminary results of Aon are presented, at 12 momenta from 500 to 1500 MeV/c. They show very large asymmetries, and a remarkable variation with energy in the newly explored low momentum region.

Spin-correlation parameters A/sub L//sub L/, A/sub S//sub L/, A/sub N//sub L/, A/sub N//sub 0/, A/sub S//sub 0/, A/sub L//sub 0/, and A/sub 0//sub L/ have been measured for the reaction pp..-->..np..pi../sup +/ at 492, 576, 643, 729, and 796 MeV. An isobar analysis determines magnitudes and phases of partial waves up to NN /sup 3/F/sub 3/. For the amplitude NN(/sup 1/D/sub 2/)..-->..N..delta..(/sup 5/S/sub 2/), the phase shows a strong threshold enhancement in the N..delta.. channel, dropping from 44.4/sup 0/ +- 4.4/sup 0/ at 492 MeV to 11.9/sup 0/ +- 1.9/sup 0/ at 796 MeV. Other phases show little activity. Broad dibaryons are conclusively ruled out in /sup 1/D/sub 2/, /sup 3/F/sub 3/, and /sup 3/P/sub 2/ in this energy range

Data on spin correlation parameters ASL, ALL and ANO for pp → π+d are reported at 492, 729 and 796 MeV. The 729 MeV ASL data are important in stabilising the amplitude analysis near that energy.

Spin correlation parameters {ital A}{sub {ital LL}}, {ital A}{sub {ital SL}},{ital A}{sub {ital NL}}, {ital A}{sub {ital NO}}, {ital A}{sub {ital SO}}, {ital A}{sub {ital LO}}, and{ital A}{sub {ital OL}} have been measured for {ital pp}{r arrow}{ital np}{pi}{sup +} at 492, 576, 643, 729, and 796 MeV over a large part of phase space, using a longitudinally polarized target and a polarized beam. Results rule out broad dibaryons in this mass range in {ital NN} {sup 3}P{sub 2} and {sup 3}F{sub 3}; in {sup 1}D{sub 2} some phase variation is observed, resembling that expected of a strong inelastic threshold.

Results are reported on the azimuthal asymmetry of antiprotons of ∼550 MeV / c , doubly scattered at small angles from protons and carbon. The measured asymmetries are small, statistically compatible with zero, and give polarization parameters smaller than those foreseen by some N N potential models.

Measurements have been made of the differential cross section and asymmetry Aon for pp elastic scattering at 15 incident momenta between 497 MeV/c and 1550 MeV/c. The angular range where both particles have enough energy to traverse target and setup has been covered. The results are compared with predictions of various NN potential models. None of these models fully explains the present results, although the general trend of the data is predicted correctly.

Asymmetries A 0 n have been measured at LEAR for s ¯ s elastic scattering for 15 beam momenta from 497 to 1550 MeV/ c .

The ratio of the real to the imaginary part of the pp forward elastic-scattering amplitude ϱ has been measured at 550, 757, and 1077 MeV/c at LEAR, using the Coulomb-nuclear interference method. The results obtained for ρ and b, the nuclear slope, are ϱ = 0.084 ± 0.051 and b = 20.9 ± 2.1 (GeV/c)−2 at 550 MeV/c, ϱ = 0.102 ± 0.043 and b = 18.0 ± 0.5 (GeV/c)−2 = at 757 MeV/c, and ϱ = 0.059 ± 0.035 and b = 15.2 ± 0.3 (GeV/c)−2 at 1077 MeV/c.

pp total cross sections have been measured from 220 to 413 MeV/ c in small (⩽ 10 MeV/ c ) steps of momentum with statistics of ± 0.5 %. There is no evidence for structure in the cross section, and a limit of 8 mb MeV/ c 2 is set with 90% confidence on the strength of any narrow resonance down to 250 MeV/ c .

Concern that relative phases of /sup 1/D/sub 2/, /sup 3/F/sub 3/, and /sup 3/P/sub 2/ NN..-->..N..delta.. partial waves determined from pp..-->..np..pi../sup +/ data from 492 to 796 MeV might allow resonances (dibaryons) has arisen. This comment is a reaffimation of our conclusion against resonances due to interference with the strong /sup 3/P/sub 1/..-->../sup 3/S/sub 1/ NN..-->..NN..pi../sup +/ (N..pi.. S waves) amplitude because the interaction is strongly repulsive. (AIP)