ISSN:
1434-6052
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract The charged hyperon beam at the CERN Super Proton Synchrotron (SPS) has been used to collect data on semileptonic decays ofΣ −,Ξ − andΛ. A magnetic channel selects 100 GeV/c negatively charged particles produced in the forward direction by interaction of the 200 GeV/c SPS proton beam on a BeO target. TheΣ − andΞ − hyperons are concurrently identified in a DISC Čerenkov counter, and their decay products are analysed by a magnetic spectrometer. Electron-hadron discrimination is achieved by the combined use of lead-glass and lead/scintillator counters, transition radiation detectors, and a Čerenkov counter. In this article we report results on the $$\Sigma ^ - \to \Lambda e^ - \bar v$$ decay mode. Measurements of the Λ polarization and of the centre-of-mass distributions (baryon kinetic energy, electron-neutrino correlation, and Dalitz plot distributions) yield the vector to axialvector form factor ratiof 1/g 1=+0.034±0.080, in agreement with the value expected from the conserved vector current hypothesis (f 1/g 1=0). TheΣ −→Λe − v→ branching ratio measurement gives a value of (5.41±0.30)×10−5. The effects of radiative corrections are not included in these results. They are discussed in the text. Results on the otherΞ −,Σ −, andΛ semileptonic decays are reported in separate articles.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01557576
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