Uncertainties from light quark loops

  • H. Burkhardt
Conference paper


The Standard Model has three input parameters (not counting fermion masses, higgs mass and mixings) that determine the couplings and masses of the vector bosons. Popular renormalization schemes use experimentally well measured quantities like the fine structure constant α = 1 / 137.0604(11) and the Fermi constant GF = 1.166344(11)·10−5 GeV−2 determined from the muon lifetime. The third parameter used to be sin2θw, determined from neutral-current processes. For LEP physics instead, will soon be measured to high precision and is therefore a good choice as third parameter. Using cosθw = MW / MZ as definition of the weak mixing angle, the tree level expression for MW becomes MW = A0 / sinθw where \({{\text{A}}_0}\, = \,\sqrt {(\pi \alpha \,/\,\sqrt 2 {{\text{G}}_{\text{F}}})} \, = \,37.281\) GeV.


Reso Neutri 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • H. Burkhardt
    • 1
  1. 1.University of SiegenGermany

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