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Cross-sections and angular distributions for hadronic and lepton pair final states in e + e − collisions at a centre-of-mass energy near 189 GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. The results are used to measure the energy dependence of the electromagnetic coupling constant α em ,(More)
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 Zγ events, and compared to Standard Model(More)
A search for pair produced scalar fermions with couplings that violate R-parity has been performed using a data sample corresponding to an integrated luminosity of 56 pb −1 at a centre-of-mass energy of √ s = 183 GeV collected with the OPAL detector at LEP. An important consequence of R-parity breaking interactions is that the lightest supersymmet-ric(More)
We present the final results of the spin asymmetries A 1 and the spin structure functions g 1 of the proton and the deuteron in the kinematic range 0.0008ϽxϽ0.7 and 0.2ϽQ 2 Ͻ100 GeV 2. For the determination of A 1 , in addition to the usual method which employs inclusive scattering events and includes a large radiative background at low x, we use a new(More)
We have searched for decays of the τ lepton into seven or more charged particles, using data collected with the OPAL detector from 1990 to 1995 in e + e − collisions at √ s ≈ M Z. No candidate events were found and an upper limit on the branching ratio for τ decays into seven charged particles of 1.8 × 10 −5 at the 95% confidence level was determined.
We have measured the spin-dependent structure function g 1 p in inclusive deep-inelastic scattering of polarized muons off polarized protons, in the kinematic range 0.003ϽxϽ0.7 and 1 GeV 2 ϽQ 2 Ͻ60 GeV 2. A next-to-leading order QCD analysis is used to evolve the measured g 1 p (x,Q 2) to a fixed Q 0 2. The first moment of g 1 p at Q 0 2 ϭ10 GeV 2 is ⌫ 1 p(More)
Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 × 10 6 hadronic Z 0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near(More)
A search is described for the neutral Higgs bosons h 0 and A 0 predicted by models with two scalar field doublets and, in particular, the Minimal Supersymmetric Standard Model (MSSM). The search in the Z 0 h 0 and h 0 A 0 production channels is based on data corresponding to an integrated luminosity of 25 pb −1 from e + e − collisions at centre-of-mass(More)