Data on muon pair production obtained by the OPAL Collaboration at centre of mass energies near the Z peak are analysed. Small angular mismatches between the directions of the two muons are used to assess the effects of initial state photon radiation and initial-final-state radiation interference on the forward–backward asymmetry of muon pairs. The dependence of the asymmetry on the invariant mass of the pair is measured in a model-independent way. Effective vector and axial-vector couplings of the Z boson are determined and compared to the Standard Model expectations.
The method originated with a co-author but was developed by Kartvelishvili and applied to OPAL data; he did 95% of the analysis and was the main author. This double-differential angular analysis of muon pair production provided an independent way of measuring the fundamental couplings of the Z boson. RAE_import_type : Journal article RAE_uoa_type : Physics