A Determination of two Michel parameters in purely leptonic tau decays
Aug, 19939 pages
Published in:
- Phys.Lett.B 316 (1993) 608-614
Report number:
- DESY-93-108
Experiments:
Citations per year
Abstract: (Elsevier)
Using the ARGUS detector at the e + e − storage ring DORIS II, we have determined the Michel parameters ϱ and ξ of τ → μν ν and τ → eν ν decays. From a data sample with 333 events/pb around s = 10 GeV , we select 3230 events e + e − → τ + τ − → (μ ± μ μ )( e ǂv v ) and determine ϱ from the e and μ momentum spectra and ξ from the correlations between e and μ momenta. For ϱ we obtain ϱ τ →e = 0.79 ± 0.08 ± 0.06 and ϱ τ → μ = 0.76 ± 0.08 in accordance with the V - A structure of the decays. The momentum correlations are only sensitive to the product ξ τ →e ξ τ → μ . Setting ξ τ →e = ξ τ → μ , we obtain | ξ τ | = 0.90 ± 0.15 ± 0.10 also in accordance with V - A. The updated decay fractions are B(τ → e v v ) = (17.5 ± 0.3 ± 0.5)% and B(τ → μv v ) = (17.4 ± 0.3 ± 0.5)% .- electron positron: colliding beams
- colliding beams: electron positron
- electron positron: annihilation
- annihilation: electron positron
- tau: electroproduction
- electroproduction: tau
- tau: pair production
- pair production: tau
- tau: leptonic decay
- leptonic decay: tau
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