Precision electroweak measurements on the Z resonance

ALEPH Collaboration, DELPHI Collaboration, L3 Collaboration, OPAL Collaboration, SLD Collaboration, LEP ElectroweakWorking Group, SLD Electroweak and Heavy Flavour Groups

Research output: Contribution to journalReview article

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Abstract

We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, mZ and ΓZ, and its couplings to fermions, for example the ρ parameter and the effective electroweak mixing angle for leptons, are precisely measured: mZ = 91.1875 ± 0.0021 GeV, ΓZ = 2.4952 ± 0.0023 GeV, ρl = 1.0050 ± 0.0010, sin2 θlept eff = 0.23153 ± 0.00016. The number of light neutrino species is determined to be 2.9840 ± 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, mt = 173+13 -10 GeV, and the mass of the W boson, mW = 80.363 ± 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of mt and mW, the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level.

Original languageEnglish
Pages (from-to)257-454
Number of pages198
JournalPhysics Reports
Volume427
Issue number5-6
DOIs
Publication statusPublished - 2006 Jan 1

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poles
asymmetry
standard deviation
bosons
fermions
quarks
decay
Higgs bosons
leptons
confidence
positrons
neutrinos
quantum chromodynamics
cross sections
predictions
electrons

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

ALEPH Collaboration, DELPHI Collaboration, L3 Collaboration, OPAL Collaboration, SLD Collaboration, LEP ElectroweakWorking Group, & SLD Electroweak and Heavy Flavour Groups (2006). Precision electroweak measurements on the Z resonance. Physics Reports, 427(5-6), 257-454. https://doi.org/10.1016/j.physrep.2005.12.006
ALEPH Collaboration ; DELPHI Collaboration ; L3 Collaboration ; OPAL Collaboration ; SLD Collaboration ; LEP ElectroweakWorking Group ; SLD Electroweak and Heavy Flavour Groups. / Precision electroweak measurements on the Z resonance. In: Physics Reports. 2006 ; Vol. 427, No. 5-6. pp. 257-454.
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abstract = "We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, mZ and ΓZ, and its couplings to fermions, for example the ρ parameter and the effective electroweak mixing angle for leptons, are precisely measured: mZ = 91.1875 ± 0.0021 GeV, ΓZ = 2.4952 ± 0.0023 GeV, ρl = 1.0050 ± 0.0010, sin2 θlept eff = 0.23153 ± 0.00016. The number of light neutrino species is determined to be 2.9840 ± 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, mt = 173+13 -10 GeV, and the mass of the W boson, mW = 80.363 ± 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of mt and mW, the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50{\%} and found to be less than 285 GeV at 95{\%} confidence level.",
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ALEPH Collaboration, DELPHI Collaboration, L3 Collaboration, OPAL Collaboration, SLD Collaboration, LEP ElectroweakWorking Group & SLD Electroweak and Heavy Flavour Groups 2006, 'Precision electroweak measurements on the Z resonance', Physics Reports, vol. 427, no. 5-6, pp. 257-454. https://doi.org/10.1016/j.physrep.2005.12.006

Precision electroweak measurements on the Z resonance. / ALEPH Collaboration; DELPHI Collaboration; L3 Collaboration; OPAL Collaboration; SLD Collaboration; LEP ElectroweakWorking Group; SLD Electroweak and Heavy Flavour Groups.

In: Physics Reports, Vol. 427, No. 5-6, 01.01.2006, p. 257-454.

Research output: Contribution to journalReview article

TY - JOUR

T1 - Precision electroweak measurements on the Z resonance

AU - ALEPH Collaboration

AU - DELPHI Collaboration

AU - L3 Collaboration

AU - OPAL Collaboration

AU - SLD Collaboration

AU - LEP ElectroweakWorking Group

AU - SLD Electroweak and Heavy Flavour Groups

AU - Bagger, J. A.

AU - Grünewald, Martin

AU - Schael, S.

AU - Barate, R.

AU - Brunelière, R.

AU - Buskulic, D.

AU - De Bonis, I.

AU - Decamp, D.

AU - Ghez, P.

AU - Goy, C.

AU - Jézéquel, S.

AU - Lees, J. P.

AU - Lucotte, A.

AU - Martin, F.

AU - Merle, E.

AU - Minard, M. N.

AU - Nief, J. Y.

AU - Odier, P.

AU - Pietrzyk, B.

AU - Trocmé, B.

AU - Bravo, S.

AU - Casado, M. P.

AU - Chmeissani, M.

AU - Comas, P.

AU - Crespo, J. M.

AU - Fernandez, E.

AU - Fernandez-Bosman, M.

AU - Garrido, Ll

AU - Grauges, E.

AU - Juste, A.

AU - Martinez, M.

AU - Merino, G.

AU - Miquel, R.

AU - Mir, Ll M.

AU - Orteu, S.

AU - Pacheco, A.

AU - Park, I. C.

AU - Perlas, J.

AU - Riu, I.

AU - Ruiz, H.

AU - Sanchez, F.

AU - Colaleo, A.

AU - Creanza, D.

AU - De Filippis, N.

AU - De Palma, M.

AU - Iaselli, G.

AU - Maggi, G.

AU - Maggi, M.

AU - Nuzzo, S.

AU - Ranieri, A.

PY - 2006/1/1

Y1 - 2006/1/1

N2 - We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, mZ and ΓZ, and its couplings to fermions, for example the ρ parameter and the effective electroweak mixing angle for leptons, are precisely measured: mZ = 91.1875 ± 0.0021 GeV, ΓZ = 2.4952 ± 0.0023 GeV, ρl = 1.0050 ± 0.0010, sin2 θlept eff = 0.23153 ± 0.00016. The number of light neutrino species is determined to be 2.9840 ± 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, mt = 173+13 -10 GeV, and the mass of the W boson, mW = 80.363 ± 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of mt and mW, the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level.

AB - We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, mZ and ΓZ, and its couplings to fermions, for example the ρ parameter and the effective electroweak mixing angle for leptons, are precisely measured: mZ = 91.1875 ± 0.0021 GeV, ΓZ = 2.4952 ± 0.0023 GeV, ρl = 1.0050 ± 0.0010, sin2 θlept eff = 0.23153 ± 0.00016. The number of light neutrino species is determined to be 2.9840 ± 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, mt = 173+13 -10 GeV, and the mass of the W boson, mW = 80.363 ± 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of mt and mW, the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level.

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ALEPH Collaboration, DELPHI Collaboration, L3 Collaboration, OPAL Collaboration, SLD Collaboration, LEP ElectroweakWorking Group et al. Precision electroweak measurements on the Z resonance. Physics Reports. 2006 Jan 1;427(5-6):257-454. https://doi.org/10.1016/j.physrep.2005.12.006