${{\mathit \tau}}$-DECAY PARAMETERS

$\eta ({{\mathit \mu}}$) PARAMETER

INSPIRE   JSON  (beta) PDGID:
S035ETM
($\mathit V−\mathit A$) theory predicts $\eta $ = $0$.
VALUE EVTS DOCUMENT ID TECN  COMMENT
$\bf{ 0.094 \pm0.073}$ OUR FIT
$\bf{ 0.17 \pm0.15}$ OUR AVERAGE  Error includes scale factor of 1.2.
$0.160$ $\pm0.150$ $\pm0.060$ 46k
HEISTER
2001E
 ALEP 1991--1995 LEP runs
$0.72$ $\pm0.32$ $\pm0.15$
ABREU
2000L
 DLPH 1992--1995 runs
$-0.59$ $\pm0.82$ $\pm0.45$ 1
ABE
1997O
 SLD 1993--1995 SLC runs
$0.010$ $\pm0.149$ $\pm0.171$ 13k 2
AMMAR
1997B
 CLEO ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $10.6$ GeV
• • We do not use the following data for averages, fits, limits, etc. • •
$0.010$ $\pm0.065$ $\pm0.001$ 27k 3
ACKERSTAFF
1999D
 OPAL 1990--1995 LEP runs
$-0.24$ $\pm0.23$ $\pm0.18$
BUSKULIC
1995D
 ALEP Repl. by HEISTER 2001E
1  Highly correlated (corr. = $0.92$) with ABE 1997O $\rho ({{\mathit \mu}}$) measurement.
2  Highly correlated (corr. = $0.949$) with AMMAR 1997B $\rho ({{\mathit \mu}}$) value.
3  ACKERSTAFF 1999D result is dominated by a constraint on $\eta $ from the OPAL measurements of the ${{\mathit \tau}}$ lifetime and B(${{\mathit \tau}^{-}}$ $\rightarrow$ ${{\mathit \mu}^{-}}{{\overline{\mathit \nu}}_{{{\mu}}}}{{\mathit \nu}_{{{\tau}}}}$) assuming lepton universality for the total coupling strength.
References