Measurement of neutral-current four-fermion production at LEP2

Abstract

Four-fermion final states qqe + e − and qqµ + µ − from neutral-current interactions in e + e − collisions are studied in the OPAL detector at LEP at centre-of-mass energies from 183 GeV to 209 GeV. The data analysed correspond to a total integrated luminosity of about 650 pb −1 recorded from 1997 to 2000. Corresponding to the acceptance of the OPAL detector, a signal definition is applied requiring both leptons to have a scattering angle satisfying | cos θ| < 0.95. Further requirements are made on the invariant masses of the fermion pairs. The extracted cross-sections for the processes e + e − → qqe + e − and e + e − → qqµ + µ − are consistent with the expectations from the Standard Model.