R.D. Tripp

The KN interaction from 800 to 1200 MeV/c (I). K−p cross sections

K−p reactions have been studied at 23 different momenta between 777 and 1226 MeV/c. This interval corresponds to a mass range of the KN system from 1688 to 1897 MeV. About 350 000 photographs were taken in the 81 cm Saclay hydrogen bubble chamber, exposed to a separated K− beam at the CERN proton synchrotron. A total of about 100 000 events were analysed and partial and differential cross sections were determined; polarisations were also obtained for those reactions where the decay of the Λ or Σ+ hyperon allowed their measurement. The data for all the channels are presented here except those corresponding to two-prong configurations, which make the subject of a separate investigation.

Measurement of the real part of the forward amplitude in pp elastic scattering

The differential cross sections of the elastic pp reaction have been measured at 1.2, 1.4, 1.8 and 2.6 GeV/c incident p momentum. The measurements have been performed at the CERN PS using a system of multiwire proportional chambers. The angular region covers scattering angles from 0 to ∼200 mrad. Interference effects between the Coulomb and the nuclear amplitudes are used to derive the ratio of the real to imaginary part of the forward nuclear amplitude. These ratios are compared with theoretical predictions.

Resonances and other partial waves in K−p → Σπ between 780 and 1220 MeV/c

Abstract A partial wave analysis of the reaction K − p → Σ + π − and Σ − π + is presented. Results are given on resonance formation in the mass region from ∼1.7 to ∼1.9 GeV.

Coulomb-nuclear interference in π±p and K±p elastic scattering below 3 GeV: Measurements, real parts and K±p dispersion relations

Abstract The differential cross sections for π + p elastic scattering at0.6, 1.0, 1.5, 2.0, GeV/ c for π - p at 1.0, 1.5, 2.0 GeV/ c , for K - p at 1.2, 1.8, 2.6 GeV/ c and for K - p at 0.9, 1.2, 1.4, 1.6, 1.8, 2.6 GeV/ c have been measured with an overall accuracy ofthe order of 1 to 2% in an electronics experiment over the angular region corresponding to momentum transfer t between 0.0005 and 0.10 GeV 2 . Making use of the interference effects between the Coulomb and the nuclear interaction, we have determined the magnitude and sign of the real part of the scattering amplitude near t = 0. The K ± p real parts have been used in a dispersion relation to derive the value of the KNΛ coupling constant.

Measurement of the real part of the forward scattering amplitude in K±p elastic scattering between 0.9 and 2.6 GeV/c

Abstract The differential cross section for K ± p elastic scattering has been measured in the forward meson direction (0.0008 t 2 ) in an electronics experiment at incident momenta between 0.9 and 2.06 GeV/ c . The high statistics and absolute normalisation of the data allow a good determination of the real part of the forward nuclear scattering amplitude by means of the Coulomb-nuclear interference effect.

The NΛK coupling constant

Abstract A dispersion relation analysis has been performed using the real parts of the K ± p forward scattering amplitudes measured over the incident momentum region from 1 to 3 GeV/ c by the electronics experiment of the preceding letter. Two possible values are found for the NΛK coupling constant. One of them is in very good agreement with the symmetry theory predictions.

K±n forward dispersion relations and the KNΣ coupling constant

Abstract Recent measurements of the K − n forward scattering amplitude at 1.2, 1.4, 2.6 GeV/ c are used in a once-subtracted dispersion relation to determine the value of the KNΣ coupling constant. The result is g Σ 2 =1.9±3.2, in agreement with the prediction of the SU(3) theory.

Measurement of the real part of the K−n forward scattering amplitude between 1.2 and 2.6 GeV/c

Abstract The differential cross sections of the combined elastic and break-up K − d reaction have been measured at 1.21, 1.42 and 2.61 GeV/ c incident K − momentum. The measurements have been performed at the CERN PS using multiwire proportional chambers. The values of the invariant momentum transfer t explored (0.0005 t | 2 ) include the Coulomb-nuclear interference region. The differential cross sections have been analysed in the framework of the Glauber impact-parameter formalism. The observed interference effects have been used to derive the ratio of the real to imaginary part of the forward K − n nuclear amplitude.

The KN interaction from 800 to 1200 MeV/c (III) a study of Λ(1520)

Abstract The resonant parameters of Λ(1520) have been determined from an analysis of the reaction sequence K − p → Σ (1760) → Λ (1520) π 0 with subsequent decay of Λ(1520) into K − p, Σ ± π ∓ and Λπ + π − . The best values for the Λ(1520) mass and width are: E R = 1517.2 ± 0.6 MeV. Γ = 14.7 ± 1.8 MeV. Its decay branching ratios are Γ(Σπ)/Γ( K N ) = 0.82 ± 0.08 and Γ(Λππ)/Γ( K N ) = 0.22 ± 0.03 and its branching fractions Γ( K N )/Λ = 0.49 ± 0.02, Γ(Σπ)/Γ = 0.40 ± 0.02. Γ(Λππ)/Γ = 0.11 ± 0.01 .

The real part of the forward scattering amplitude in π±p elastic scattering below 2 GeV/c

Abstract The differential cross section for π ± p elastic scattering below 2 GeV/ c has been measured at small forward pion angles by an electronics experiment. The interference effects observed between the Coulomb and the nuclear interaction have been used to determine the magnitude and sign of the real parts of the π ± p forward scattering amplitude. The latter are compared to the values predicted by the dispersion relations.