The elastic scattering of K+ mesons on protons is studied at 3.5 and 5 GeV/c. The total elastic cross-sections are found to be (4.36±0.36) mb and (3.82±0.41) mb respectively. The differential elastic cross-sections, which exhibit characteristic diffraction peaks, are fitted by dσ/dt=(dσ/dt)0eαt, giving α=(3.85±0.12) and (4.70±0.21) (GeV/c)−2 for the two momenta respectively, with |t|⪝0.65 (GeV/c)2. The results are compared to those at neighbouring energies, giving some support to the presence of a real part of the forward scattering amplitude. The diffraction peak shows definite shrinking with increasing momenta. The data are examined in the light of models for high-energy scattering.
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The transmission regeneration amplitude after a thick copper block has been measured. The quantity {∣ƒ(0)- overlineƒ(0)∣ }/{k} varies from 20.0 $\pm$ 1.4 mb at 2.75 GeV/c to 13.6 $\pm$ 1.2 mb at 7.25 GeV/c. Results are in agreement with optical model calculations in which real and imaginary parts of the amplitudes for single nucleon scattering are determined from forward dispersion relations and total cross-sections.
Regeneration amplitude.
Differential cross sections and polarizations have been measured for the reaction π − p → K 0 Λ and π − p → K 0 Σ 0 at 3.9 GeV/ c π − momentum. Comparison of these data with those of the related reactions K − n → π − Λ and K − p → π − Σ + (at approximately the same c.m. energy) indicate that simple Regge-pole models involving only K ∗ (890) and K ∗ (1420) exchange are unable to describe all the features of the data. On the other hand, comparison of the π − p → K 0 Σ 0 data with that of π + p → K + Σ + shows that the data are consistent with absence of exotic strange-meson exchange.
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We report on coherent interactions in a 2.5 event/μb K − d exposure. The predominant channel studied is K − d → K − π + gp − d (415 events). We find strong Q- and L-production in the (K ππ ) system. The production mechanism determines I = 1 2 for both enhancements and a spin-parity in the series 0 − , 1 + ,2 − … . A spin-parity analysis shows the Q to be a 1 + object, while the L is 1 + or 2 − , although a higher spin cannot be excluded. The cross sections for Q and L production and other final states are presented.
CORRECTED FOR UNSEEN RECOIL DEUTERONS BY EXTRAPOLATION. (UNCORRECTED CROSS SECTIONS ARE THOSE OBSERVED WITH P(DEUT) > 140 MEV/C).
The differential cross-sections for the annihilation processes p p→π − π + and p p→K − K + have been measured at an incident laboratory momentum at 5 GeV/ c . Strong backward and forward peaks are observed in the π + π − differential cross-sections while the K + K − cross-section is shown to have a peak only for K − going forward. The annihilation cross-sections are compared with the cross-sections for the crossed channel backward processes π ± p→p π ± and K ± p→pK ± .
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The proof is given for the existence of the reaction e + e − → h ± h ∓ in the energy range 1400–2400 MeV, and its energy dependence is compared with that of e + e − → e ± e ∓ , in the same experimental conditions of observation. The exponent of the s -dependence of the ratio α = (e + e − → h ± h ∓ )/ (e + e − → e ± e ∓ ) is measured to be n = 2.08 ± 0.45, in the s -range (1.96 − 5.76) GeV 2 , on the basis of 51 e + e − → h ± h ∓ events and 8918 e + e − → e ± e ∓ events observed.
CROSS SECTION FOR PRODUCTION OF CHARGED HADRON PAIRS.
In this paper we present the results of an analysis of strange-particle production in π−p collisions leading to two charged final particles and at least one strange neutral decay. The sample consists
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A study of π − p → K ∗ Λ and π − p → K ∗ Σ° at 3.9 GeV /c indicates that the main features of both reactions can be interpreted in terms of simple exchange processes, the first involving both natural and unnatural exchange, the second showing evidence for natural parity exchange only.
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The elastic scattering of K ± mesons on protons has been studied at 5 GeV/c. A total of about 500 000 events have been measured in the c.m. angular range 17° < θ cm < 165° corresponding to 0.2 < − t < (GeV/ c ) 2 . We observed a K − p backward peak which we have parametrized as d σ /d u = (0.6 ± 0.2) exp [(3.3 ± 0.6) u ] μb /(GeV/c) 2 , while for the K + p backward peak we find d σ /d u = (17.5 ± 1) exp [(3.6 ± 0.2) u ] μb /(GeV/c) 2 . The K − p cross-section falls to about 0.03 μ b ( GeV /c) 2 around − t = 5 (GeV/ c ) 2 , while the K + p cross-section stays in the vicinity of 0.3 μ b ( GeV /c) 2 in the same t -region. The K + p and K − p differential cross-sections have cross-over points at − t = 0.2, 1.1 and about 3.5 (GeV/ c ) 2 .
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