Abbiendi, G;
Ainsley, C;
Åkesson, PF;
Alexander, G;
Allison, J;
Anagnostou, G;
Anderson, KJ;
... Hanson, GG; + view all
(2001)
Precise determination of the Z resonance parameters at LEP: "Zedometry".
European Physical Journal C
, 19
(4)
pp. 587-651.
10.1007/s100520100627.
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Abstract
This final analysis of hadronic and leptonic cross-sections and of leptonic forward-backward asymmetries in e+e- collisions with the OPAL detector makes use of the full LEP 1 data sample comprising 161pb-1 of integrated luminosity and 4.5 × 106 selected Z decays. An interpretation of the data in terms of contributions from pure Z exchange and from γ/Z interference allows the parameters of the Z resonance to be determined in a model-independent way. Our results are in good agreement with lepton universality and consistent with the vector and axial-vector couplings predicted in the Standard Model. A fit to the complete dataset yields the fundamental Z resonance parameters: mz = (91.1852 ± 0.0030) GeV, Γz = (2.4948 ± 0.0041) GeV, σ0h = (41.501 ± 0.055) nb, Rℓ = 20.823 ± 0.044, and A0,ℓFB = 0.0145 ± 0.0017. Transforming these parameters gives a measurement of the ratio between the decay width into invisible particles and the width to a single species of charged lepton, Γinv/Γℓℓ = 5.942 ± 0.027. Attributing the entire invisible width to neutrino decays and assuming the Standard Model couplings for neutrinos, this translates into a measurement of the effective number of light neutrino species, Nv = 2.984 ± 0.013. Interpreting the data within the context of the Standard Model allows the mass of the top quark, mt = (162+29-16) GeV, to be determined through its influence on radiative corrections. Alternatively, utilising the direct external measurement of mt as an additional constraint leads to a measurement of the strong coupling constant and the mass of the Higgs boson: αs(mz) = 0.127 ± 0.005 and mH = (390+750-280)GeV.
Type: | Article |
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Title: | Precise determination of the Z resonance parameters at LEP: "Zedometry" |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1007/s100520100627 |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
URI: | https://discovery.ucl.ac.uk/id/eprint/9837 |
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