Measurement of the Michel parameters and the average τ neutrino helicity from τ decays in e+e− → τ+τ−
Copyright policy )Measurement of the Michel parameters and the average τ neutrino helicity from τ decays in e+e− → τ+τ−
Abstract The Michel parameters ϱ, η, ξ, and ξδ, the chirality parameter ξ h and the τ polarization P τ are measured using 32012 τ pair decays. Their values are extracted from the energy spectra of leptons and hadrons in τ − → l − ν l ν τ and τ − → π − ν τ decays, the energy and decay angular distributions in τ − → ϱ − ν τ decays, and the correlations in the energy spectra and angular distributions of the decay products. Assuming universality in leptonic and semileptonic τ decays, the results are ϱ = 0.794±0.039±0.031, η = 0.25±0.17±0.11, ξ = 0.94±0.21±0.07, ξδ = 0.81±0.14±0.06, ξ h = −0.970±0.053±0.011, and P τ = −0.154±0.018±0.012. The measurement is in agreement with the V-A hypothesis for the weak charged current.
- Johns Hopkins University United States
- College of New Jersey United States
- Radboud University Nijmegen Netherlands
- Helmholtz Association of German Research Centres Germany
- University of California, San Diego United States
annihilation: electron positron, POLARIZATION, energy spectrum, electron positron: annihilation, pair production: tau, tau- --> rho(770)- neutrino/tau, angular distribution, tau: polarization, info:eu-repo/classification/ddc/530, model: weak interaction, electroproduction: Z0, MUON DECAY, tau: pair production, leptonic decay: tau, semileptonic decay: tau, tau- --> lepton neutrino/tau antineutrino, Michel parameter, CERN LEP Stor, electron positron: colliding beams, weak interaction: model, tau- --> pi- neutrino/tau, approx. 91 GeV-cms, colliding beams: electron positron, correlation, L3, ASYMMETRY, tau: leptonic decay, MUON DECAY; POLARIZATION; ASYMMETRY, polarization: tau, Particle Physics - Experiment, Z0: electroproduction, tau: semileptonic decay, experimental results
annihilation: electron positron, POLARIZATION, energy spectrum, electron positron: annihilation, pair production: tau, tau- --> rho(770)- neutrino/tau, angular distribution, tau: polarization, info:eu-repo/classification/ddc/530, model: weak interaction, electroproduction: Z0, MUON DECAY, tau: pair production, leptonic decay: tau, semileptonic decay: tau, tau- --> lepton neutrino/tau antineutrino, Michel parameter, CERN LEP Stor, electron positron: colliding beams, weak interaction: model, tau- --> pi- neutrino/tau, approx. 91 GeV-cms, colliding beams: electron positron, correlation, L3, ASYMMETRY, tau: leptonic decay, MUON DECAY; POLARIZATION; ASYMMETRY, polarization: tau, Particle Physics - Experiment, Z0: electroproduction, tau: semileptonic decay, experimental results
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