${{\mathit \tau}}$ WEAK DIPOLE MOMENT ($\mathit d{}^{\mathit w}_{{{\mathit \tau}} }$)

A nonzero value is forbidden by $\mathit CP$ invariance.
The $\mathit q{}^{2}$ dependence is expected to be small providing no thresholds are nearby.

Im($\mathit d{}^{\mathit w}_{{{\mathit \tau}} }$)

INSPIRE  
VALUE ($ 10^{-17} $ $\mathit e~$cm) CL% DOCUMENT ID TECN  COMMENT
$\bf{<1.1}$ 95 1
HEISTER
2003F
 ALEP $1990 - 1995$ LEP runs
• • We do not use the following data for averages, fits, limits, etc. • •
$<1.5$ 95
ACKERSTAFF
1997L
 OPAL 1991--1995 LEP runs
$<4.5$ 95 2
AKERS
1995F
 OPAL Repl. by ACKERSTAFF 1997L
1  HEISTER 2003F limit is on the absolute value of the imaginary part of the weak dipole moment.
2  Limit is on the absolute value of the imaginary part of the weak dipole moment, and applies for $\mathit q{}^{2}$ = ${{\mathit m}^{2}}_{{{\mathit Z}}}$.
Conservation Laws:
$\mathit CP$ INVARIANCE
References:
HEISTER 2003F
EPJ C30 291 Search for Anomalous Weak Dipole Moments of the ${{\mathit \tau}}$ Lepton
ACKERSTAFF 1997L
ZPHY C74 403 Search for $\mathit CP$ Violation in ${{\mathit Z}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}$ and an Upper Limit on the Weak Dipole Moment of the ${{\mathit \tau}}$ Lepton
AKERS 1995F
ZPHY C66 31 A Test of $\mathit CP$ Invariance in ${{\mathit Z}^{0}}$ $\rightarrow$ ${{\mathit \tau}^{+}}{{\mathit \tau}^{-}}$ using Optimal Observables