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

($\delta \xi )({{\mathit e}}$ or ${{\mathit \mu}}$) PARAMETER

INSPIRE   PDGID:
S035DXI
($\mathit V−\mathit A$) theory predicts ($\delta \xi $) = $0.75$.
VALUE EVTS DOCUMENT ID TECN  COMMENT
$\bf{ 0.746 \pm0.021}$ OUR FIT
$\bf{ 0.744 \pm0.022}$ OUR AVERAGE
$0.776$ $\pm0.045$ $\pm0.024$ 81k
HEISTER
2001E
ALEP 1991--1995 LEP runs
$0.779$ $\pm0.070$ $\pm0.028$ 36k
ABREU
2000L
DLPH 1992--1995 runs
$0.65$ $\pm0.14$ $\pm0.07$ 46k
ACKERSTAFF
1999D
OPAL 1990--1995 LEP runs
$0.70$ $\pm0.11$ 54k
ACCIARRI
1998R
L3 $1991 - 1995$ LEP runs
$0.63$ $\pm0.09$ 1
ALBRECHT
1998
ARG ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $9.5 - 10.6$ GeV
$0.88$ $\pm0.27$ $\pm0.04$ 2
ABE
1997O
SLD 1993--1995 SLC runs
$0.745$ $\pm0.026$ $\pm0.009$ 55k
ALEXANDER
1997F
CLEO ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $10.6$ GeV
• • We do not use the following data for averages, fits, limits, etc. • •
$0.81$ $\pm0.14$ $\pm0.06$ 18k
ACCIARRI
1996H
L3 Repl. by ACCIARRI 1998R
$0.65$ $\pm0.12$ 3
ALBRECHT
1995C
ARG Repl. by ALBRECHT 1998
$0.88$ $\pm0.11$ $\pm0.07$
BUSKULIC
1995D
ALEP Repl. by HEISTER 2001E
1  Combined fit to ARGUS tau decay parameter measurements in ALBRECHT 1998, ALBRECHT 1995C, ALBRECHT 1993G, and ALBRECHT 1994E. ALBRECHT 1998 use tau pair events of the type ${{\mathit \tau}^{-}}$ ${{\mathit \tau}^{+}}$ $\rightarrow({{\mathit \ell}^{-}}{{\overline{\mathit \nu}}_{{{{{\mathit \ell}}}}}}{{\mathit \nu}_{{{\tau}}}})({{\mathit \pi}^{+}}{{\mathit \pi}^{0}}{{\overline{\mathit \nu}}_{{{\tau}}}}$), and their charged conjugates.
2  ABE 1997O assume $\eta $ = 0 in their fit. Letting $\eta $ vary in the fit gives a ($\delta \xi $) value of $0.87$ $\pm0.27$ $\pm0.04$.
3  Combined fit to ARGUS tau decay parameter measurements in ALBRECHT 1995C, ALBRECHT 1993G, and ALBRECHT 1994E. ALBRECHT 1995C uses events of the type ${{\mathit \tau}^{-}}$ ${{\mathit \tau}^{+}}$ $\rightarrow$ (${{\mathit \ell}^{-}}{{\overline{\mathit \nu}}_{{{{{\mathit \ell}}}}}}{{\mathit \nu}_{{{\tau}}}}$ ) (${{\mathit h}^{+}}{{\mathit h}^{-}}{{\mathit h}^{+}}{{\overline{\mathit \nu}}_{{{\tau}}}}$ ) and their charged conjugates.
References