Measurement of the $B$ baryon lifetime and branching fractions in $Z$ decays

ALEPH Collaboration, The and Barate, R. and Betteridge, Andrew and Bowdery, Christopher and Colrain, Paul and Finch, Alexander and Foster, Frank and Hughes, Gareth and Jones, Roger and Sloan, Terence and Williams, Mark (1998) Measurement of the $B$ baryon lifetime and branching fractions in $Z$ decays. European Physical Journal C: Particles and Fields, 2 (2). pp. 197-211. ISSN 1434-6044

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 Λℓ− combinations, the average b baryon lifetime is measured to be 1.20±0.08±0.06 ps. From a sample of 193 fully reconstructed Λ+c candidates correlated with a lepton and a sample of 46 Λℓ+ℓ− combinations, the Λb lifetime is measured to be 1.21±0.11 ps. The product branching fractions to these final states are Br(b→Λb⋅BR(Λb→Λℓ−ν¯X)=0.326±0.016±0.039 % for the first sample and Br(b→Λb⋅BR(Λb→Λ+cℓ−ν¯X)=0.86±0.07±0.14 % for the second and third samples combined.