EPJ

2018 Impact factor 4.843
EPJ C - Particles and Fields
Particles and Fields
Eur. Phys. J. C 2, 197-211

Measurement of the b baryon lifetime and branching fractions in Z decays

The ALEPH Collaboration, R. Barate et al.

Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS, F-74019 Annecy-le-Vieux Cedex, France

Received: 15 August 1997

Abstract
Using approximately 4 million hadronic Z decays recorded with the ALEPH detector from 1991 through 1995, the lifetime of the b baryon is measured with three independent methods. From the impact parameter distribution of candidate leptons in 1063 events with $\Lambda\ell^-$combinations, the average b baryon lifetime is measured to be $1.20\pm{0.08}\pm{0.06}$ ps. From a sample of 193 fully reconstructed $\Lambda_{\mathrm c}^{+}$ candidates correlated with a lepton and a sample of 46 $\Lambda\ell^{+}\ell^{-}$ combinations, the $\Lambda_{\mathrm b}$ lifetime is measured to be $1.21\pm{0.11}$ ps. The product branching fractions to these final states are ${Br}({\mathrm b}\rightarrow{\Lambda}_{\mathrm b})\cdot{Br}({\Lambda}_{\mathrm b... ...ghtarrow\Lambda\ell^{-}\overline{\nu}\mathrm{X})= 0.326\pm{0.016}\pm{0.039}\,\%$for the first sample and ${Br}({\mathrm b}\rightarrow{\Lambda}_{\mathrm b})\cdot{Br}({\Lambda}_{\mathrm b... ...da_{\mathrm c}^{+}\ell^{-}\overline{\nu}\mathrm{X})= 0.86\pm{0.07}\pm{0.14}\,\%$ for the second and third samples combined.

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