${{\boldsymbol Z}}$ AXIAL-VECTOR COUPLINGS

These quantities are the effective axial-vector couplings of the ${{\mathit Z}}$ to charged leptons. Their magnitude is derived from a measurement of the ${{\mathit Z}}$ lineshape and the forward-backward lepton asymmetries as a function of energy around the ${{\mathit Z}}$ mass. The relative sign among the vector to axial-vector couplings is obtained from a measurement of the ${{\mathit Z}}$ asymmetry parameters, ${{\mathit A}_{{e}}}$, ${{\mathit A}_{{\mu}}}$, and ${{\mathit A}_{{\tau}}}$. By convention the sign of $\mathit g{}^{{{\mathit e}}}_{\mathit A}$ is fixed to be negative (and opposite to that of $\mathit g{}^{{{\mathit \nu}_{{e}}}}$ obtained using ${{\mathit \nu}_{{e}}}$ scattering measurements). For the light quarks, the sign of the couplings is assigned consistently with this assumption. The fit values quoted below correspond to global nine- or five-parameter fits to lineshape, lepton forward-backward asymmetry, and ${{\mathit A}_{{e}}}$, ${{\mathit A}_{{\mu}}}$, and ${{\mathit A}_{{\tau}}}$ measurements. See the note ``The ${{\mathit Z}}$ boson'' and ref. LEP-SLC 2006 for details. Where ${{\mathit p}}{{\overline{\mathit p}}}$ and ${{\mathit e}}{{\mathit p}}$ data is quoted, OUR FIT value corresponds to a weighted average of this with the LEP/SLD fit result.

$\boldsymbol g{}^{{{\boldsymbol \mu}}}_{\boldsymbol A}$ INSPIRE search

VALUE EVTS DOCUMENT ID TECN  COMMENT
$\bf{ -0.50120 \pm0.00054}$ OUR FIT
$-0.50117$ $\pm0.00099$ 182.8K 1
ABBIENDI
2001O
OPAL ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$-0.5009$ $\pm0.0014$ 113.4k 2
ACCIARRI
2000C
L3 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$-0.50046$ $\pm0.00093$
BARATE
2000C
ALEP ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
$-0.520$ $\pm0.015$ 66143 3
ABBIENDI
2001K
OPAL ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $89 - 93$ GeV
1  ABBIENDI 2001O use their measurement of the ${{\mathit \tau}}$ polarization in addition to the lineshape and forward-backward lepton asymmetries.
2  ACCIARRI 2000C use their measurement of the ${{\mathit \tau}}~$polarization in addition to forward-backward lepton asymmetries.
3  ABBIENDI 2001K obtain this from an angular analysis of the muon pair asymmetry which takes into account effects of initial state radiation on an event by event basis and of initial-final state interference.
  References:
ABBIENDI 2001K
PL B516 1 Angular Analysis of the Muon Pair Asymmetry at LEP I
ABBIENDI 2001O
EPJ C21 1 Precision Neutral Current Asymmetry Parameter Measurements from the ${{\mathit \tau}}$ Polarization at LEP
ACCIARRI 2000C
EPJ C16 1 Measurements of Cross Sections and Forward Backward Asymmetries at the ${{\mathit Z}}$ Resonance and Determination of Electroweak Parameters
BARATE 2000C
EPJ C14 1 Measurement of the ${{\mathit Z}}$ Resonance Parameters at LEP