Tests of the standard model and constraints on new physics from measurements of fermion-pair production at 130–172 GeV at LEP

  • The OPAL Collaboration
  • K. Ackerstaff et al.
Experimental physics


Production of events with hadronic and leptonic final states has been measured in \({\rm e^+e^-}\) collisions at centre-of-mass energies of 130–172 GeV, using the OPAL detector at LEP. Cross-sections and leptonic forward-backward asymmetries are presented, both including and excluding the dominant production of radiative Z\(\gamma\) events, and compared to Standard Model expectations. The ratio \(R_{\rm b}\) of the cross-section for \({\rm b\bar b}\) production to the hadronic cross-section has been measured. In a model-independent fit to the Z lineshape, the data have been used to obtain an improved precision on the measurement of \(\gamma\)-Z interference. The energy dependence of \(\alpha_{\mathrm{em}}\) has been investigated. The measurements have also been used to obtain limits on extensions of the Standard Model described by effective four-fermion contact interactions, to search for \(t\)-channel contributions from new massive particles and to place limits on gaugino pair production with subsequent decay of the gaugino into a light gluino and a quark pair.


Pair Production Energy Dependence Massive Particle Opal Detector Contact Interaction 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • The OPAL Collaboration
  • K. Ackerstaff et al.
    • 1
  1. 1. CERN, European Organisation for Particle Physics, CH-1211 Geneva 23, Switzerland CH

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