Correlation measurements in Z ---> tau+ tau- and the tau-neutrino helicity

Using data collected with the ALEPH detector at LEP correlations between the decay products of the τ + and τ − produced in the decay of the Z have been measured. The measurements performed in the decays τ → πν and τ → ϱν place limits on deviations from the Standard Model. These are given by the parameter ζ with ζ = −1 for the Standard Model. The measured values are ζ π = −0.95 ± 0.11 ± 0.05 and ζ ϱ = −1.03 ± 0.11 ± 0.05. For models which predict ζ π = ζ ϱ = ζ — interpreted as the average τ neutrino helicity — the measurement is ζ = −0.99 ± 0.07 ± 0.04.

electron positron: colliding beams
colliding beams: electron positron
electron positron: annihilation
annihilation: electron positron
Z0: electroproduction
electroproduction: Z0
Z0: nonleptonic decay
nonleptonic decay: Z0
tau: pair production
pair production: tau

References(14)

Figures(0)

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