The reaction
pp→
K
+
Λp was measured exclusively at the cooler synchrotron COSY at beam momenta of p
Beam = 2.50
GeV/c and p
Beam = 2.75
GeV/c using the TOF detector. Angular and momentum ...distributions were obtained for the full phase space of the reaction products. Total cross sections were extracted to be (2.7 ± 0.3)
μb and (12.0 ± 0.4)
μb, respectively. The polarization of the
Λ-hyperon was determined as a function of its transversal momentum and was found to be negative for transverse momentum transfers of p
T
≥ 0.3
GeV/c. The results together with existing data are compared with phenomenological parametrizations and model calculations on the basis of meson exchange.
Spin-transfer observables for p p-->Lambda Lambda have been measured using a transversely polarized frozen-spin target and a beam momentum of 1.637 GeV/c. Current models of the reaction near ...threshold are in good agreement with existing measurements performed with unpolarized particles in the initial state but produce conflicting predictions for the spin-transfer observables Dnn and Knn (the normal-to-normal depolarization and polarization transfer), which are measurable only with polarized target or beam. Measurements of Dnn and Knn presented here are found to be in disagreement with predictions from these models.
The reaction
p
p→
Λ
Λ
was examined by LEAR experiment PS185/3 at 1.525 and 1.640 GeV/c. The proton target was transversely polarized in order to measure the depolarization and spin transfer. ...Theoretical calculations of
D
nn, the component of the depolarization normal to the production plane, differ greatly according to whether quark-gluon or meson-exchange models are employed. The measured
D
nn and spin transfer
K
nn appear to be inconsistent with the specific models cited.
The PS185 experiment at LEAR/CERN has investigated strangeness production in p̄p collisions with final states such as Λ̄Λ, Σ0Λ+c.c, Σ+Σ+, Σ−Σ− and KSKS. Results are presented from a study of about ...32000 KSKSX events obtained at several p̄ momenta in the regions of 1.45 and 1.7 GeV/c. The p̄p→KSKSη cross sections extracted at these momenta constitute the first measurement of this reaction in flight and are broadly consistent with expectations of a phase-space extrapolation of branching ratios from annihilation at rest.
The ({sup 6}Li,{sup 6}He) reaction was studied on targets of {sup 12}C, {sup 18}O, {sup 26}Mg, and {sup 42}Ca at a beam energy of 156 MeV. Zero degree measurements of all systems are presented. The ...evaluated cross sections for Gamow-Teller transitions at {theta}=0{degree} and the corresponding strengths of analogous beta decays are compared.
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