OPAL Physics Note PN462 6th October 2000 Measurement of Standard Model Processes in

Based on the analysis of about 175 pb of data in e e collisions at centre-of-mass energies between 203 GeV and 209 GeV recorded with the OPAL detector at LEP, several preliminary measurements and comparisons with the Standard Model expectations are described. In particular, results on crosssections for hadronic, lepton pair, and multi-photon nal states and on forward-backward asymmetries for the leptonic nal states are presented. Preliminary determinations of the cross-sections for WW and ZZ production are described. QCD studies of hadronic events are also presented at these highest e centre-of-mass energies. All results are consistent with Standard Model expectations

OPAL Physics Note PN437 18th July 2000 Measurement of Standard Model Processes in

Based on the analysis of about 87 pb of data in e collisions at centre-of-mass energies between 203 GeV and 209 GeV recorded with the OPAL detector at LEP, several preliminary measurements and comparisons with the Standard Model expectations are described. In particular, results on crosssections for hadronic, lepton pair, and multi-photon final states and on forward-backward asymmetries for the leptonic final states are presented. These results are used to determine the electromagnetic coupling constant ff em at LEP2 energies and to put limits on new physics. Preliminary determinations of the cross-sections for WW and ZZ production are described. QCD studies of hadronic decays are also presented at these highest e centre-of-mass energies. All results are consistent with Standard Model expectations

Measurement of Standard Model Processes in e+e- Collisions at √s >202 GeV

Based on the analysis of about 205 pb of data in e e collisions at centre-of-mass energies between 203 GeV and 209 GeV recorded with the OPAL detector at LEP, several preliminary measurements and comparisons with the Standard Model expectations are described. In particular, results on crosssections for hadronic, lepton pair, and multi-photon nal states and on forward-backward asymmetries for the leptonic nal states are presented. Preliminary determinations of the cross-sections for WW and ZZ production are described. All results are consistent with Standard Model expectations

PN423 3 March 2000 Z Boson Pair Production in e

A study of Z boson pair production in e e - annihilation at center-of-mass energies above 190 GeV using the OPAL detector at LEP is reported. Final states containing only leptons, (# # - and # - ##), quark and lepton pairs, (qq# # - , qq##) and only quarks (qqqq) have been studied. In all states with at least one Z boson decaying hadronically, qq and bb final states are considered separately using lifetime and event-shape tags, thereby improving the cross-section measurement. The Z-pair cross-section measurements are which are consistent with the Standard Model prediction. Limits on anomalous ZZ# and ZZZ couplings are derived