2012 Impact factor 5.247
EPJ C - Particles and Fields
Particles and Fields
Open Access
Eur. Phys. J. C 2, 441-472
DOI 10.1007/s100529800851

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.Ackerstaff8 et al.

8 CERN, European Organisation for Particle Physics, CH-1211 Geneva 23, Switzerland

Received: 30 July 1997 / Published online: 10 March 1998

Abstract
Production of events with hadronic and leptonic final states has been measured in 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 $\mathrm{Z}$$\gamma$ events, and compared to Standard Model expectations. The ratio $R_{\rm b}$ of the cross-section for $\mathrm{b}\overline{\mathrm{b}}$ production to the hadronic cross-section has been measured. In a model-independent fit to the $\mathrm{Z}$ lineshape, the data have been used to obtain an improved precision on the measurement of $\gamma$-$\mathrm{Z}$ 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.


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