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Searches for the neutral Higgs bosons h 0 and A 0 are used to obtain limits on the Type II Two Higgs Doublet Model (2HDM(II)) with no CP–violation in the Higgs sector and no additional particles besides the five Higgs bosons. The analysis combines approximately 170 pb −1 of data collected with the OPAL detector at √ s ≈ 189 GeV with previous runs at √ s ≈ m(More)
  • G Abbiendi, K Ackerstaff, +141 authors Heisenberg Fellow
  • 1999
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)
  • G Abbiendi, K Ackerstaff, +164 authors Heisenberg Fellow
  • 1997
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)
BACKGROUND There is a broad literature suggesting that cognitive difficulties are associated with violence across a variety of groups. Although neurocognitive and social cognitive deficits are core features of schizophrenia, evidence of a relationship between cognitive impairments and violence within this patient population has been mixed. METHODS We(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)
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)
Cross-sections for hadronic and leptonic two-fermion events, and leptonic forward-backward asymmetries, have been measured in e + e ? collisions at a centre-of-mass energy of 161 GeV, using the OPAL detector at LEP. Results are presented both including and excluding the dominant production of radiative Z 0 events. We have measured R b , the ratio of the(More)
The process e + e ? ! e + e ? Z== is studied with the OPAL detector at LEP at a centre of mass energy of p s = 189 GeV. The cross-section times the branching ratio of the Z== decaying into hadrons is measured within Lorentz invariant kinematic limits to be (1:2 0:30:1) pb for invariant masses of the hadronic system between 5 GeV and 60 GeV and (0:7 0:20:1)(More)
The production of charged hadrons and K 0 S mesons in the collisions of quasi-real photons has been measured using the OPAL detector at LEP. The data were taken at e + e − centre-of-mass energies of 161 and 172 GeV. The differential cross-sections as a function of the transverse momentum and the pseudorapidity of the charged hadrons and K 0 S mesons have(More)
Helicity density matrix elements for inclusive K * (892) 0 mesons from hadronic Z 0 decays have been measured over the full range of K * 0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x p values above 0.3, with the matrix element ρ 00 rising to 0.66 ±(More)