Improved tau polarization measurement
Collaboration
22 pages
Published in:
- Z.Phys.C 69 (1996) 183-194
DOI:
Report number:
- CERN-PPE-95-023,
- CERN-PPE-95-23
Experiments:
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Citations per year
Abstract:
Using 22 pb−1 of data collected at LEP in 1992 on the peak of the Z resonance, the ALEPH collaboration has measured the polarisation of the tau leptons decaying intoevv¯,μvv¯,πν, ρν and a1 ν from their individual decay product distributions. The measurement of the tau polarisation as a function of the production polar angle yields the two parametersN τ andN e, where, in terms of the axial and vector couplingsg Al andg Vl,N l=2g Vl gAl/(g Vl 2 +g Al 2 ). This analysis follows to a large extent the methods devised for the 1990 and 1991 data but with improvements which bring a better understanding of the systematic uncertainties. Combining the 1992 measurements with our previously published results yieldsN τ=0.136±0.012±0.009 andN e=0.129±0.016±0.005. Assuminge−τ universality, the measurements imply an effective weak mixing angle of sin 2 θ W eff =0.2332±0.0014.- electron positron: colliding beams
- colliding beams: electron positron
- electron positron: annihilation
- annihilation: electron positron
- Z0: electroproduction
- electroproduction: Z0
- tau: pair production
- pair production: tau
- tau: leptonic decay
- leptonic decay: tau
References(17)
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