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Precision Electroweak Measurements on the Z resonance.

Jones, Roger W. L. and Borissov, Guennadi and Grunewald, M. W. and Ratoff, Peter N. and Smizanska, Maria (2006) Precision Electroweak Measurements on the Z resonance. Physics Reports, 427 (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: 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, , and the mass of the W boson, . 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 at 95% confidence level.

Item Type: Article
Journal or Publication Title: Physics Reports
Additional Information: This paper summarizes the LEP I electroweak measurements that both test the theory and allow prediction of a wide range of processes. Jones worked on the heavy flavour and inclusive charge asymmetry combinations and chapters, and was chief editor for the inclusive charge asymmetry chapter. 154 citations (SPIRES). RAE_import_type : Journal article RAE_uoa_type : Physics
Uncontrolled Keywords: Electron–positron physics ; Electroweak interactions ; Decays of heavy intermediate gauge bosons ; Fermion–antifermion production ; Precision measurements at the Z resonance ; Tests of the Standard Model ; Radiative corrections ; Effective coupling constants ; Neutral weak current ; Z boson ; W boson ; Top quark ; Higgs boson
Subjects: Q Science > QC Physics
Departments: Faculty of Science and Technology > Physics
ID Code: 2308
Deposited By: ep_importer
Deposited On: 03 Apr 2008 16:18
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 16:09
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/2308

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