In an experiment on K--proton interactions in a hydrogen bubble chamber, the cross sections and angular distributions have been studied for elastic and charge-exchange scattering, and charged sigma hyperon production in the momentum range 90-300 MeV/c. Good agreement is found with previous cross sections except for the charge-exchange channel where the new values are 60% larger. The production distributions of the charged sigma hyperons and the polarisation of the Sigma + hyperon clearly indicate that P waves are present down to about 150 MeV/c, much lower than previously reported.
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Differential cross sections for elastic K + p scattering have been measured at nineteen momenta between 0.7 and 1.9 GeV/ c . The data represent between 10 thousand and 20 thousand elastic events at each momentum and cover a wide range of scattering angles ( −0.98 ≲ cos θ ∗ ≲ 0.95 ). A computer controlled system of scintillation counters and acoustic spark chambers was used to detect the elastic events. Various internal consistency checks indicate that the absolute normalization of the data is accurate to within 2–3%. The cross sections show a smooth transition from an isotropic angular distribution to a dominant forward peak over the range covered by the experiment. Phase-shift analyses including these results show little evidence for a direct-channel resonance, and fitting the results by t - and u -channel exchange processes alone gives a good fit.
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Differential cross sections for π−p elastic scattering over the angular range 155° to 177° in the center-of-mass system have been measured at 33 incident pion momenta in the range 600 to 1280 MeV/c. The experiment, which was performed at the Bevatron at the Lawrence Berkeley Laboratory, employed a liquid hydrogen target, a double-arm spectrometer, and standard counter techniques to detect the elastic events. The data from this experiment are compared to all other published data in this momentum region. The over-all agreement is good. The data of this experiment are also compared with the results of the recent phase-shift analysis by Almehed and Lovelace. In the momentum region between 700 and 900 MeV/c, the slope of the backward angular distribution goes rapidly through zero from negative to positive, and the magnitude of the differential cross section falls by more than a factor of 10. Momentum-dependent structure is seen in the extrapolated differential cross sections at 180°. Two prominent dips in the 180° differential cross sections appear at 880 and 1150 MeV/c. This structure is discussed in terms of a direct-channel resonance model that assumes only resonant partial waves are contributing to the cross sections for large scattering angles.
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The differential cross section for K ± p elastic scattering has been measured in the very low t region (0.003 < t < 0.2 GeV 2 ) in a wire chamber spectrometer experiment at 10.4 and 14 GeV/ c . The interference effect observed between the Coulomb and the nuclear interaction has been used to determine α, the ratio of real to imaginary part of the forward scattering amplitude. At 10.4 GeV/ c we measure α (K + p) = −0.21 ± 0.06 and α (K − p = 0.08 ± 0.04, and at 14 GeV/ c , α (K + p) = − 0.13 ± 0.03 and α (K − p) = 0.000 ± 0.04 in agreeement with the predictions of dispersion theory calculation.
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The differential cross-section for π - -p elastic scattering over the angular range 125° to 178° center of mass has been measured between 1.28 and 3.0 GeV/ c . Considerable structure is found and is discussed in terms of direct channel resonances.
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Large-angle π±p elastic-scattering cross sections, measured between 2 and 9 GeV/c in fine intervals of incident momentum and scattering angle, are used to search for cross-section fluctuations occurring for small changes in the center-of-mass energy as suggested by Ericson and Mayer-Kuckuck and by Frautschi. Significant fluctuations are observed.
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