The production and decay of beauty baryons (b-baryons) have been studied using 1.7 x 10(6) Z hadronic decays collected by the DELPHI detector at LEP. Three different techniques were used to identify the b-baryons. The first method used pairs of a Lambda and a lepton to tag the b-baryon decay. The second method associated fully reconstructed Lambda(c) baryons with leptons. The third analysis reconstructed the b-baryon decay points by forming secondary vertices from identified protons and muons of opposite sign. Using these methods the following production rates were measured: f(b --> b-baryon) x BR(b-baryon --> Lambda l nu(l)X) = (0.30 +/- 0.06 +/- 0.04)%, f(b --> b-baryon) x BR(b-baryon --> Lambda(c)l nu(l)X) = (1.18 +/- 0.26(-0.21)(+0.31)%, f(b --> b-baryon) x BR(b-baryon --> p mu nu(mu)X) = (0.49 +/- 0.11 +/- (+0.15)(-0.11)%. The average b-baryon lifetime was determined to be: tau = 1.21(-0.18)(+.21)(stat.) +/- 0.04(exp.syst.)(-.07)(+.02)(th.syst,) ps.
Lifetime and production-rate of beauty baryons from Z-decays
PREST, MICHELA;
1995-01-01
Abstract
The production and decay of beauty baryons (b-baryons) have been studied using 1.7 x 10(6) Z hadronic decays collected by the DELPHI detector at LEP. Three different techniques were used to identify the b-baryons. The first method used pairs of a Lambda and a lepton to tag the b-baryon decay. The second method associated fully reconstructed Lambda(c) baryons with leptons. The third analysis reconstructed the b-baryon decay points by forming secondary vertices from identified protons and muons of opposite sign. Using these methods the following production rates were measured: f(b --> b-baryon) x BR(b-baryon --> Lambda l nu(l)X) = (0.30 +/- 0.06 +/- 0.04)%, f(b --> b-baryon) x BR(b-baryon --> Lambda(c)l nu(l)X) = (1.18 +/- 0.26(-0.21)(+0.31)%, f(b --> b-baryon) x BR(b-baryon --> p mu nu(mu)X) = (0.49 +/- 0.11 +/- (+0.15)(-0.11)%. The average b-baryon lifetime was determined to be: tau = 1.21(-0.18)(+.21)(stat.) +/- 0.04(exp.syst.)(-.07)(+.02)(th.syst,) ps.
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