Title 



Precision electroweak measurements on the Z resonance
 
Author 



 
Abstract 



We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electronpositron 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 crosssections, forwardbackward 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: View the MathML source 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 Zpole, 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 Zpole measurements, the forwardbackward asymmetry in bquark 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 Zpole data are also used to predict the mass of the top quark, View the MathML source, and the mass of the W boson, View the MathML source. 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 View the MathML source at 95% confidence level.   
Language 



English
 
Source (journal) 



Physics reports.  Amsterdam  
Publication 



Amsterdam : 2006
 
ISSN 



03701573
 
Volume/pages 



427:5/6(2006), p. 257454
 
ISI 



000236815000001
 
Full text (Publisher's DOI) 


  
