Measurement of the polarization of tau leptons produced in e/sup +/e/sup -/ annihilation at. sqrt. s = 29 GeV

Journal Article · Thu Oct 01 00:00:00 EDT 1987 · Phys. Rev. D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.36.1971· OSTI ID:6146262

Ford, W T; Qi, N; Read, Jr, A L; Smith, J G; Camporesi, T; De Sangro, R; Peruzzi, I; Piccolo, M; Hurst, R B; Pyrlik, J; others, and

We present measurements of forward-backward energy asymmetries of tau-lepton decay products from the reaction e/sup +/e/sup -/..-->..tau/sup +/tau/sup -/ in data collected with the MAC detector operating at the SLAC storage ring PEP at a center-of-mass energy of 29 GeV. The energy asymmetries for the decays tau..--> nu../sub tau/enu-bar/sub e/, tau..--> nu../sub tau/..mu..nu-bar/sub ..mu../, tau..--> nu../sub tau/..pi.., and tau..--> nu../sub tau/rho are interpreted as effects caused by the combination of maximally parity-violating weak tau decays and a longitudinal polarization produced by the interference of electromagnetic and weak processes. From the forward-backward polarization asymmetry A/sub P/ = (0.06 +- 0.07) x (1 +- 0.011), we determine the coupling-constant product g/sub a//sup e/g/sub v//sup tau/ = (0.26 +- 0.31) x (1 +- 0.011). Assuming g/sub a//sup e/ = -(1/2 as expected, we find g/sup tau//sub v/ = (-0.52 +- 0.62) x (1 +- 0.011), consistent with the prediction of the Glashow-Weinberg-Salam model of electroweak interactions. Alternatively, assuming the standard-model prediction of negligible polarization in tau-pair production, the leptonic energy spectra are used to measure the Michel parameter to be 0.79 +- 0.10 +- 0.10, consistent with the V-A hypothesis for the taunu-bar/sub tau/-W vertex.

• Research Organization: Department of Physics, University of Colorado, Boulder, Colorado 80309
• OSTI ID: 6146262
• Journal Information: Phys. Rev. D; (United States), Journal Name: Phys. Rev. D; (United States) Vol. 36:7; ISSN PRVDA
• Country of Publication: United States
• Language: English

Related Subjects

645101 -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
645102* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Weak Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANNIHILATION
ASYMMETRY
BASIC INTERACTIONS
BOSONS
COUPLING CONSTANTS
CROSS SECTIONS
DATA
DECAY
ELECTROMAGNETIC INTERACTIONS
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
EXPERIMENTAL DATA
FERMIONS
FIELD THEORIES
GEV RANGE
GEV RANGE 10-100
HADRONS
HEAVY LEPTONS
INFORMATION
INTERACTIONS
LEPTON-LEPTON INTERACTIONS
LEPTONIC DECAY
LEPTONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MESONS
MUONS
NEUTRINOS
NUMERICAL DATA
PAIR PRODUCTION
PARTICLE DECAY
PARTICLE INTERACTIONS
PARTICLE MODELS
PIONS
POLARIZATION
POSTULATED PARTICLES
PSEUDOSCALAR MESONS
RHO-765 RESONANCES
SEMILEPTONIC DECAY
STANDARD MODEL
TAU PARTICLES
UNIFIED GAUGE MODELS
UNIFIED-FIELD THEORIES
V-A THEORY
WEAK INTERACTIONS
WEAK PARTICLE DECAY
WEINBERG-SALAM GAUGE MODEL