Measurement of Neutral-Current Four-Fermion Production at LEP2

TL;DR

This paper measures neutral-current four-fermion production in electron-positron collisions at LEP2, confirming consistency with the Standard Model through detailed cross-section analysis of specific final states.

Contribution

First measurement of neutral-current four-fermion production at LEP2 energies, providing experimental validation of Standard Model predictions for these processes.

Findings

Measured cross-sections agree with Standard Model expectations

Analyzed data from 183 to 209 GeV with 650 pb-1 luminosity

Confirmed neutral-current four-fermion production in specified final states

Abstract

Four-fermion final states qqbar e+e- and qqbar mu+mu- 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 cos0 <0.95. Further requirements are made on the invariant masses of the fermion pairs. The extracted cross-sections for the processes e+e- -> qqbar e+e- and e+e- qqbar mu+mu- are consistent with the expectations from the Standard Model.