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

These quantities are the effective axial-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.

$\mathit g{}^{{{\mathit d}}}_{\mathit A}$

INSPIRE   PDGID:
S044GDA
VALUE EVTS DOCUMENT ID TECN  COMMENT
$\bf{ -0.527 {}^{+0.040}_{-0.028}}$ OUR AVERAGE
$-0.619$ $\pm0.108$ 1
ANDREEV
2018A
 H1 ${{\mathit e}^{\pm}}{{\mathit p}}$
$-0.497$ $\pm0.165$ 156k 2
ABAZOV
2011D
 D0 ${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$ = 1.97 TeV
$-0.52$ ${}^{+0.05}_{-0.03}$ 3
LEP-SLC
2006
${\it{}E}^{\it{}ee}_{\rm{}cm}$ = $88 - 94$ GeV
$-0.016$ ${}^{+0.346}_{-0.536}$ $\pm0.091$ 5026 4
ACOSTA
2005M
 CDF ${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 1.96~TeV
• • We do not use the following data for averages, fits, limits, etc. • •
$-0.56$ ${}^{+0.41}_{-0.15}$ 5
ABRAMOWICZ
2016A
 ZEUS
$-0.409$ ${}^{+0.373}_{-0.213}$ 6
ABT
2016
$-0.80$ $\pm0.24$ 1500 7
AKTAS
2006
H1 ${{\mathit e}^{\pm}}$ ${{\mathit p}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{{e}}}}({{\mathit \nu}_{{{e}}}}){{\mathit X}}$, $\sqrt {s }\approx{}$300 GeV
1  ANDREEV 2018A obtain this result in a combined electroweak and QCD analysis using all deep-inelastic ${{\mathit e}^{+}}{{\mathit p}}$ and ${{\mathit e}^{-}}{{\mathit p}}$ neutral current and charged current scattering cross sections published by the H1 Collaboration, including data with longitudinally polarized lepton beams.
2  ABAZOV 2011D study ${{\mathit p}}$ ${{\overline{\mathit p}}}$ $\rightarrow$ ${{\mathit Z}}$ /${{\mathit \gamma}^{*}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ events using 5 fb${}^{-1}$ data at $\sqrt {s }$ = 1.96 TeV. The candidate events are selected by requiring two isolated electromagnetic showers with $\mathit E_{T}>$ 25 GeV, at least one electron in the central region and the di-electron mass in the range $50 - 1000$ GeV. From the forward-backward asymmetry, determined as a function of the di-electron mass, they derive the axial and vector couplings of the ${{\mathit u}}$- and ${{\mathit d}}$- quarks and the value of sin$^2\theta {}^{{{\mathit \ell}}}_{eff}$ = $0.2309$ $\pm0.0008$(stat)$\pm0.0006$(syst).
3  LEP-SLC 2006 is a combination of the results from LEP and SLC experiments using light quark tagging. s- and d-quark couplings are assumed to be identical.
4  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 the light quarks, assuming the electron couplings are as predicted by the Standard Model. Higher order radiative corrections have not been taken into account.
5  ABRAMOWICZ 2016A determine the ${{\mathit Z}^{0}}$ couplings to ${{\mathit u}}$- and ${{\mathit d}}$-quarks using the ZEUS polarised data from Run II together with the unpolarised data from both ZEUS and H1 Collaborations for Run I and unpolarised H1 data from Run II.
6  ABT 2016 determine the ${{\mathit Z}^{0}}$ couplings to ${{\mathit u}}$- and ${{\mathit d}}$-quarks using the same techniques and data as ABRAMOWICZ 2016A but additionally use the published H1 polarised data.
7  AKTAS 2006 fit the neutral current (1.5${}\leq{}Q{}^{2}{}\leq{}$30,000 GeV${}^{2}$) and charged current (1.5${}\leq{}Q{}^{2}{}\leq{}$15,000 GeV${}^{2}$) differential cross sections. In the determination of the ${{\mathit d}}$-quark couplings the electron and ${{\mathit u}}$-quark couplings are fixed to their standard model values.
References