${{\boldsymbol Z}}$ MASS INSPIRE search

OUR FIT is obtained using the fit procedure and correlations as determined by the LEP Electroweak Working Group (see the note ``The ${{\mathit Z}}$ boson'' and ref. LEP-SLC 2006 ). The fit is performed using the ${{\mathit Z}}$ mass and width, the ${{\mathit Z}}$ hadronic pole cross section, the ratios of hadronic to leptonic partial widths, and the ${{\mathit Z}}$ pole forward-backward lepton asymmetries. This set is believed to be most free of correlations.

The ${{\mathit Z}}$-boson mass listed here corresponds to the mass parameter in a Breit-Wigner distribution with mass dependent width. The value is 34 MeV greater than the real part of the position of the pole (in the energy-squared plane) in the ${{\mathit Z}}$-boson propagator. Also the LEP experiments have generally assumed a fixed value of the ${{\mathit \gamma}}$ $−$ ${{\mathit Z}}$ interferences term based on the standard model. Keeping this term as free parameter leads to a somewhat larger error on the fitted ${{\mathit Z}}$ mass. See ACCIARRI 2000Q and ABBIENDI 2004G for a detailed investigation of both these issues.

VALUE (GeV) EVTS DOCUMENT ID TECN  COMMENT
$\bf{ 91.1876 \pm0.0021}$ OUR FIT
$91.1852$ $\pm0.0030$ 4.57M 1
ABBIENDI
2001A
OPAL ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$91.1863$ $\pm0.0028$ 4.08M 2
ABREU
2000F
DLPH ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$91.1898$ $\pm0.0031$ 3.96M 3
ACCIARRI
2000C
L3 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
$91.1885$ $\pm0.0031$ 4.57M 4
BARATE
2000C
ALEP ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
$91.1872$ $\pm0.0033$ 5
ABBIENDI
2004G
OPAL ${\it{}E}^{\it{}ee}_{\rm{}cm}$= LEP1 + $130 - 209$ GeV
$91.272$ $\pm0.032$ $\pm0.033$ 6
ACHARD
2004C
L3 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $183 - 209$ GeV
$91.1875$ $\pm0.0039$ 3.97M 7
ACCIARRI
2000Q
L3 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= LEP1 + $130 - 189$ GeV
$91.151$ $\pm0.008$ 8
MIYABAYASHI
1995
TOPZ ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $57.8$ GeV
$91.74$ $\pm0.28$ $\pm0.93$ 156 9
ALITTI
1992B
UA2 ${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 630 GeV
$90.9$ $\pm0.3$ $\pm0.2$ 188 10
ABE
1989C
CDF ${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= $1.8$ TeV
$91.14$ $\pm0.12$ 480 11
ABRAMS
1989B
MRK2 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $89 - 93$ GeV
$93.1$ $\pm1.0$ $\pm3.0$ 24 12
ALBAJAR
1989
UA1 ${\it{}E}^{\it{}p\overline{\it{}p}}_{\rm{}cm}$= 546,630 GeV
1  ABBIENDI 2001A error includes approximately $2.3$ MeV due to statistics and $1.8$ MeV due to LEP energy uncertainty.
2  The error includes $1.6$ MeV due to LEP energy uncertainty.
3  The error includes $1.8$ MeV due to LEP energy uncertainty.
4  BARATE 2000C error includes approximately $2.4$ MeV due to statistics, $0.2~$MeV due to experimental systematics, and $1.7~$MeV due to LEP energy uncertainty.
5  ABBIENDI 2004G obtain this result using the S$-$matrix formalism for a combined fit to their cross section and asymmetry data at the ${{\mathit Z}}$ peak and their data at $130 - 209$ GeV. The authors have corrected the measurement for the 34 MeV shift with respect to the Breit$-$Wigner fits.
6  ACHARD 2004C select ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit \gamma}}$ events with hard initial$-$state radiation. Z decays to ${{\mathit q}}{{\overline{\mathit q}}}$ and muon pairs are considered. The fit results obtained in the two samples are found consistent to each other and combined considering the uncertainty due to ISR modelling as fully correlated.
7  ACCIARRI 2000Q interpret the $\mathit s$-dependence of the cross sections and lepton forward-backward asymmetries in the framework of the S-matrix formalism. They fit to their cross section and asymmetry data at high energies, using the results of S-matrix fits to ${{\mathit Z}}$-peak data (ACCIARRI 2000C) as constraints. The $130 - 189$ GeV data constrains the ${{\mathit \gamma}}/{{\mathit Z}}$ interference term. The authors have corrected the measurement for the $34.1$ MeV shift with respect to the Breit-Wigner fits. The error contains a contribution of $\pm2.3$ MeV due to the uncertainty on the ${{\mathit \gamma}}{{\mathit Z}}$ interference.
8  MIYABAYASHI 1995 combine their low energy total hadronic cross-section measurement with the ACTON 1993D data and perform a fit using an S-matrix formalism. As expected, this result is below the mass values obtained with the standard Breit-Wigner parametrization.
9  Enters fit through ${{\mathit W}}/{{\mathit Z}}$ mass ratio given in the ${{\mathit W}}$ Particle Listings. The ALITTI 1992B systematic error ($\pm0.93$) has two contributions: one ($\pm0.92$) cancels in ${\mathit m}_{{{\mathit W}}}/{\mathit m}_{{{\mathit Z}}}$ and one ($\pm0.12$) is noncancelling. These were added in quadrature.
10  First error of ABE 1989 is combination of statistical and systematic contributions; second is mass scale uncertainty.
11  ABRAMS 1989B uncertainty includes 35 MeV due to the absolute energy measurement.
12  ALBAJAR 1989 result is from a total sample of 33 ${{\mathit Z}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ events.
  References:
ABBIENDI 2004G
EPJ C33 173 Tests of the Standard Model and Constraints on New Physics from Measurements of Fermion Pair Production at 189 to 209 GeV at LEP
ACHARD 2004C
PL B585 42 Measurement of the ${{\mathit Z}}$ Boson Mass using ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit \gamma}}$ Events at Center of Mass Energies above the Z Pole
ABBIENDI 2001A
EPJ C19 587 Precise Determination of the ${{\mathit Z}}$ Resonance Parameters at LEP: ``Zedometry''
ABREU 2000F
EPJ C16 371 Cross Sections and Leptonic Forward-Backward Asymmetries from the ${{\mathit Z}^{0}}$ Running of LEP
ACCIARRI 2000C
EPJ C16 1 Measurements of Cross Sections and Forward Backward Asymmetries at the ${{\mathit Z}}$ Resonance and Determination of Electroweak Parameters
ACCIARRI 2000Q
PL B489 93 Determination of ${{\mathit \gamma}}/{{\mathit Z}}$ Interference in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at LEP
BARATE 2000C
EPJ C14 1 Measurement of the ${{\mathit Z}}$ Resonance Parameters at LEP
MIYABAYASHI 1995
PL B347 171 Measurement of the Total Hadronic Cross Section and Determination of ${{\mathit \gamma}}{{\mathit Z}}$ Interference in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation
ALITTI 1992B
PL B276 354 An Improved Determination of the Ratio of ${{\mathit W}}$ and ${{\mathit Z}}$ Masses at the CERN ${{\overline{\mathit p}}}{{\mathit p}}$ Collider
ABE 1989C
PRL 63 720 Measurement of the Mass and Width of ${{\mathit Z}^{0}}$ Boson at the Fermilab Tevatron
ABRAMS 1989B
PRL 63 2173 Measurements of ${{\mathit Z}^{0}}$-Boson Resonance Parameters in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation
ALBAJAR 1989
ZPHY C44 15 Studies of Intermediate Vector Boson Production and Decay in UA1 at the CERN Proton-Antiproton Collider