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A measurement of the τ − → µ−ν¯µντ branching ratio

Research output: Contribution to journalJournal article

  • OPAL Collaboration
<mark>Journal publication date</mark>2/01/2003
<mark>Journal</mark>Physics Letters B
Issue number1-2
Number of pages14
Pages (from-to)35-48
<mark>Original language</mark>English


The τ− → µ−ν¯µντ branching ratio has been measured using data collected from 1990 to 1995 by the OPAL detector at the LEP collider. The resulting value of B(τ− → µ−ν¯µντ ) = 0.1734 ± 0.0009(stat) ± 0.0006(syst) has been used in conjunction with other OPAL measurements to test lepton universality, yielding the coupling constant ratios gµ/ge = 1.0005 ± 0.0044 and gτ /ge = 1.0031 ± 0.0048, in good agreement with the Standard Model prediction of unity. A value for the Michel parameter η = 0.004 ± 0.037 has also been determined and used to find a limit for the mass of the charged Higgs boson, mH± > 1.28 tan β, in the Minimal Supersymmetric Standard Model.