Measurement of the average b-baryon lifetime and the product branching ratio {Mathematical expression}

The OPAL Collaboration

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The average lifetime of b-flavoured baryons measured with the OPAL detector is updated to include data collected between 1990 and 1994 at LEP. Bottom-flavoured baryons that decay semileptonically and produce a Λ baryon are identified through the correlation of the baryon number of the Λ and the electric charge of the lepton. To measure the lifetime, the decay point of the b baryon is estimated by the Λ-lepton vertex, and the observed distribution of decay lengths is fitted simultaneously in 874 right-sign and 384 wrong-sign combinations. In a separate method, the impact parameter distribution of the leptons is fitted in a subset of these data. When the two results are combined, taking correlations into account, the average b-baryon lifetime is found to be τ=1.16±0.11(stat.)±0.06(syst.) ps. Using the same data, the product branching ratio is measured to be {Mathematical expression}, where the symbol f(b→Λ b) is the fraction of b quarks from Z0 decays forming b baryons, Λ b represents all b-flavoured baryons and ℓ is either an electron or a muon.

Original languageEnglish
Pages (from-to)195-214
Number of pages20
JournalEuropean Physical Journal C
Issue number1
StatePublished - 1 Dec 1995
Externally publishedYes

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)


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