OUR EVALUATION 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 ). Corrections as discussed in VOUTSINAS 2020 and JANOT 2020 are also included. This quantity is defined as

$\sigma{}{}^{0}_{\mathit h}$ = ${12 {{\mathit \pi}}\over \mathit M{}^{2}_{{{\mathit Z}}}}{\Gamma\mathrm {( {{\mathit e}^{+}} {{\mathit e}^{-}} )}~\Gamma\mathrm {({\mathrm {hadrons}})}\over \Gamma {}^{2}_{{{\mathit Z}}}}$

It is one of the parameters used in the ${{\mathit Z}}$ lineshape fit.

VALUE (nb) EVTS DOCUMENT ID TECN  COMMENT $\bf{ 41.4802 \pm0.0325}$ OUR EVALUATION $41.4802$ $\pm0.0325$ 1 JANOT 2020 • • We do not use the following data for averages, fits, limits, etc. • • $41.500$ $\pm0.037$ 2 VOUTSINAS 2020 $41.541$ $\pm0.037$ LEP-SLC 2006 ${\it{}E}^{\it{}ee}_{\rm{}cm}$ = $88 - 94$ GeV $41.501$ $\pm0.055$ 4.10M 3 ABBIENDI 2001 A OPAL ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV $41.578$ $\pm0.069$ 3.70M ABREU 2000 F DLPH ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV $41.535$ $\pm0.055$ 3.54M ACCIARRI 2000 C L3 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV $41.559$ $\pm0.058$ 4.07M 4 BARATE 2000 C ALEP ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $88 - 94$ GeV $42$ $\pm4$ 450 ABRAMS 1989 B MRK2 ${\it{}E}^{\it{}ee}_{\rm{}cm}$= $89.2 - 93.0$ GeV 1  JANOT 2020 applies a correction to LEP-SLC 2006 using an updated Bhabha cross section calculation. This result also includes a correction to account for correlated luminosity bias as presented in VOUTSINAS 2020 . 2  VOUTSINAS 2020 applies a correction to LEP-SLC 2006 to account for correlated luminosity bias. 3  ABBIENDI 2001A error includes approximately 0.031 due to statistics, 0.033 due to event selection systematics, 0.029 due to uncertainty in luminosity measurement, and 0.011 due to LEP energy uncertainty. 4  BARATE 2000C error includes approximately $0.030$ due to statistics, $0.026$ due to experimental systematics, and $0.025$ due to uncertainty in luminosity measurement.

References:

JANOT 2020 PL B803 135319 Improved Bhabha cross section at LEP and the number of light neutrino species VOUTSINAS 2020 PL B800 135068 Beam-beam effects on the luminosity measurement at LEP and the number of light neutrino species LEP-SLC 2006 PRPL 427 257 Precision Electroweak Measurements on the ${{\mathit Z}}$ Resonance 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 BARATE 2000C EPJ C14 1 Measurement of the ${{\mathit Z}}$ Resonance Parameters at LEP ABRAMS 1989B PRL 63 2173 Measurements of ${{\mathit Z}^{0}}$-Boson Resonance Parameters in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation