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AbstractAbstract
[en] The results presented in this thesis test the validity of classical Cabibbo theory. The WA2 experiment at the CERN SPS has taken data on semi-leptonic decays of the Λ0, Σ- and Ψ- strange hyperons, members of the 1/2+ baryon octet. The use of a lead glass wall combined with two transition radiation detectors suppresses the main background coming from hadronic decays Ψ- → Λπ-. The final samples are composed of 200 Ψ- → Σ0e-antiν, 1600 Σ- → Λe-antiν, 2600 Ψ- → Λe-antiν, 5000 Σ- → ne-antiν and 7200 Λ → pe-antiν. Branching ratios are computed with an experimental uncertainty of 5 % and provide a first determination of the form factors. The fit of the Dalitz plot and the angular asymmetries relative to the Λ polarisation yield the value and the sign of the ratio of axial to vector form factors. All these results are compatible with classical 3-parameter cabibbo theory and considerably enhance the present world statistics
[fr]
Les resultats presentes dans cette these ont pour but de tester la validite de la theorie classique de Cabibbo. L'experience WA2 a pris des donnees au SPS du CERN sur les desintegrations semi-leptoniques des hyperons etranges Λ0, Σ- et Ψ-, membres de l'octet des baryons 1/2+. Le bruit de fond principal, compose d'evenements hadroniques Ψ- → Λπ- est elimine au moyen d'un mur de verre au plomb et de deux detecteurs a radiation de transition. Les echantillons finals comprennent 200 Ψ- → Σ0e-antiν, 1600 Σ- → Λe-antiν, 2600 Ψ- → Λe-antiν, 5000 Σ- → ne-antiν et 7200 Λ → pe-antiν. Les rapports de branchement sont mesures avec une erreur experimentale de 5 % et donnent une premiere determination des facteurs de forme. Le fit du diagramme de Dalitz et des asymetries angulaires relatives a la polarisation du Λ permet de determiner le signe et la valeur du rapport des facteurs de forme axial et vectoriel. L'ensemble des resultats est compatible avec la theorie classique de Cabibbo a 3 parametres et ameliore considerablement la statistique mondiale actuelleOriginal Title
Desintegrations semi-leptoniques d'hyperons
Primary Subject
Source
Jul 1981; 255 p; These (D. es Sc.).
Record Type
Report
Literature Type
Thesis/Dissertation; Numerical Data
Report Number
Country of publication
BASIC INTERACTIONS, CHARGED PARTICLE DETECTION, DATA, DECAY, ELEMENTARY PARTICLES, FERMIONS, HADRONS, INFORMATION, INTERACTIONS, LIE GROUPS, MEASURING INSTRUMENTS, NUMERICAL DATA, PARTICLE DECAY, PARTICLE PROPERTIES, RADIATION DETECTION, SPECTROMETERS, STRANGE PARTICLES, SU GROUPS, SYMMETRY GROUPS, WEAK PARTICLE DECAY
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