Determination of the structure of tau decays in the reaction e+ e- ---> tau+ tau- ---> rho+ anti-tau-neutrino rho- tau-neutrino and a precision measurement of the tau-neutrino helicity
Jul, 199412 pages
Published in:
- Phys.Lett.B 337 (1994) 383-392
Report number:
- DESY-94-120
Experiments:
Citations per year
Abstract: (Elsevier)
Using the ARGUS detector at the DORIS II storage ring we have investigated the Lorentz structure of the electroweak interaction in semi-hadronic τ decays. Spin correlations in the process e + e − → τ + τ − → v τ π + π 0 v τ π − π 0 are exploited for a measurement of the normalized product of the vector ( g V ) and axial vector ( g A ) couplings of the τ lepton, γin AV = 2 Re {g A g V ∗ } (|g V | 2 ) . The correlations are sensitive to the product of the couplings in both τ decays: γ AV 2 = γ AV (τ − → ν τ W − ) AV = −h(v τ )h( v τ ) . The measured value, γ AV 2 = 1.044±0.057±0.060, determines the relative sign of the neutrino helicities. Assuming CP invariance, the absolute value | γ AV | = 1.022±0.028±0.030 was found to be incellent agreement with the Standard Model. The contribution of scalar ( g s ) or pseudoscalar ( g P ) couplings was also investigated. No evidence for a scalar-like coupling was found.- 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: semileptonic decay
- semileptonic decay: tau
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