Abbiendi, G; Ainsley, C; Åkesson, PF; Alexander, G; Allison, J; Anagnostou, G; Anderson, KJ; ... Hanson, GG; + view all Abbiendi, G; Ainsley, C; Åkesson, PF; Alexander, G; Allison, J; Anagnostou, G; Anderson, KJ; Arcelli, S; Asai, S; Ashby, SF; Axen, D; Azuelos, G; Bailey, I; Ball, AH; Barberio, E; Barlow, RJ; Behnke, T; Bell, KW; Bella, G; Bellerive, A; Benelli, G; Bentvelsen, S; Beeston, C; Bethke, S; Biebel, O; Bloodworth, IJ; Boeriu, O; Bock, P; Böhme, J; Bonacorsi, D; Boutemeur, M; Braibant, S; Bright-Thomas, P; Brigliadori, L; Brown, RM; Burckhart, HJ; Cammin, J; Capiluppi, P; Carnegie, RK; Caron, B; Carter, AA; Carter, JR; Chang, CY; Charlton, DG; Clarke, PEL; Clay, E; Cohen, I; Conboy, JE; Cooke, OC; Couchman, J; Coxe, RL; Csilling, A; Cuffiani, M; Dado, S; Dallavalle, GM; Dallison, S; Darling, C; de Roeck, A; de Wolf, EA; Dervan, P; Desch, K; Dienes, B; Dixit, MS; Donkers, M; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, IP; Estabrooks, PG; Etzion, E; Fabbri, F; Fanti, M; Feld, L; Ferrari, P; Fiedler, F; Fleck, I; Ford, M; Foucher, M; Frey, A; Fürtjes, A; Futyan, DI; Gagnon, P; Gascon, J; Gascon-Shotkin, SM; Gary, JW; Gaycken, G; Geich-Gimbel, C; Giacomelli, G; Giacomelli, P; Giacomelli, R; Glenzinski, D; Goldberg, J; Grandi, C; Graham, K; Gross, E; Grunhaus, J; Gruwé, M; Günther, PO; Hajdu, C; Hanson, GG; - view fewer (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.

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