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Measurement of the strong coupling constant using T decays

Research output: Contribution to journalJournal article


<mark>Journal publication date</mark>1993
<mark>Journal</mark>Physics Letters B
Issue number1-2
Number of pages12
Pages (from-to)209-220
<mark>Original language</mark>English


The strong coupling constant is determined from the leptonic branching ratios, the lifetime, and the invariant mass distribution of the hadronic final state of the τ lepton, using data accumulated at LEP with the ALEPH detector. The strong coupling constant measurement, αs(mτ2) = 0.330±0.046, evolved to the Z mass yields αs(MZ2) = 0.188±0.005. The error includes experimental and theoretical uncertainties, the latter evaluated in the framework of the Shifman, Vainshtein and Zakharov (SVZ) approach. The method allows the non-perturbative contribution to the hadronic decay rate to be determined to be 0.3±0.5%.