${{\mathit Z}}$ VECTOR COUPLINGS

These quantities are the effective vector couplings of the ${{\mathit Z}}$ to charged leptons and quarks. 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 LEP/SLD-based 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.

$\mathit g{}^{{{\mathit e}}}_{\mathit V}$

INSPIRE   JSON  (beta) PDGID:
S044GEV
VALUE EVTS DOCUMENT ID TECN  COMMENT
$\bf{ -0.03817 \pm0.00047}$ OUR FIT
$-0.058$ $\pm0.016$ $\pm0.007$ 5026 1
ACOSTA
2005M
CDF ${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 1.96~TeV
$-0.0346$ $\pm0.0023$ 137.0k 2
ABBIENDI
2001O
OPAL ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$-0.0412$ $\pm0.0027$ 124.4k 3
ACCIARRI
2000C
L3 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$-0.0400$ $\pm0.0037$
BARATE
2000C
ALEP ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$-0.0414$ $\pm0.0020$ 4
ABE
1995J
SLD ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $91.31$ GeV
1  ACOSTA 2005M determine the forward--backward asymmetry of ${{\mathit e}^{+}}{{\mathit e}^{-}}$ pairs produced via ${{\mathit q}}$ ${{\overline{\mathit q}}}$ $\rightarrow$ ${{\mathit Z}}/{{\mathit \gamma}^{*}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ in 15 M(${{\mathit e}^{+}}{{\mathit e}^{-}}$) effective mass bins ranging from 40~GeV to~600 GeV. These results are used to obtain the vector and axial--vector couplings of the ${{\mathit Z}}$ to ${{\mathit e}^{+}}{{\mathit e}^{-}}$, assuming the quark couplings are as predicted by the standard model. Higher order radiative corrections have not been taken into account.
2  ABBIENDI 2001O use their measurement of the ${{\mathit \tau}}$ polarization in addition to the lineshape and forward-backward lepton asymmetries.
3  ACCIARRI 2000C use their measurement of the ${{\mathit \tau}}~$polarization in addition to forward-backward lepton asymmetries.
4  ABE 1995J obtain this result combining polarized Bhabha results with the $\mathit A_{\mathit LR}$ measurement of ABE 1994C. The Bhabha results alone give $-0.0507$ $\pm0.0096$ $\pm0.0020$.
References