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Article
Hyperon production in lead-lead interactions at 40 and 160 A GeV/c
The NA57 experiment has measured strange baryon and antibaryon production in Pb-Pb collisions at 40 A GeV/c and 160 A GeV/c beam momenta. This presentation covers strangeness enhancement and transverse spectra fr...
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Article
A, Ξ and Ω enhancement at central rapidity in Pb-Pb collisions at 158A GeV/ c
A, Ξ and Ω yields and transverse mass spectra have been measured in Pb-Pb and p-Pb collisions at 158A GeV/c. The yields in Pb-Pb interactions are presented as a function of the collision centrality and compared w...
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Article
Determination of the production rate of D*0 mesons and of the ratio V/(V+P) in \(Z^0 \to c\bar c\) decays
In e+e2212 collisions at centre-of-mass energies around 91 GeV, D*0 mesons have been reconstructed using data collected with the OPAL detector at LEP. The hadronisation fraction has been measured to be f(c→D*0)=0...
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Article
A search for neutral Higgs bosons in the MSSM and models with two scalar field doublets
A search is described for the neutral Higgs bosons h0 and A0 predicted by models with two scalar field doublets and, in particular, the Minimal Supersymmetric Standard Model (MSSM). The search in the Z0h0 and h0A
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Article
Multi-photon final states in e+e− collisions at ∝s =130-172 GeV
The process e+e− →, γγ(γ) is studied using data recorded with the OPAL detector at LEP. The data sample corresponds to a total integrated luminosity of 25.38 pb−1 taken at centre-of-mass energies of 130–172 GeV. ...
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Article
Search for unstable heavy and excited leptons in e+e− collisions at ∝s = 170-172 GeV
We have searched for unstable neutral and charged heavy leptons, N and L±, and for excited states of neutral and charged leptons, ν* e*, μ* and τ*, in e+e− collisions at centre-of-mass energies of 170 and 172 GeV...
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Article
Search for a massive Di-photon resonance at ∝s = 91 – 172 GeV
A search for the resonant production of high mass photon pairs associated with a leptonic or hadronic system has been performed using a total data sample of 25.7 pb−1 taken at centre-of-mass energies between 130 ...
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Article
Σ+, Σ0 and Σ− hyperon production in hadronic Z0 decays
The production rates of the $J_{P}={1⩈er 2}^{+}$ octet Σ baryons in hadronic Z0 decays have been measured using the OPAL detector at LEP. The inclusive production rates per hadronic Z0 decay of the three isospin ...
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Article
A measurement of the charm and bottom forward-backward asymmetries using D mesons at LEP
A measurement of the charm and bottom forward-backward asymmetry in e+e− annihilations is presented at energies on and around the peak of the Z0 resonance. Decays of the Z0 into charm and bottom quarks are tagged...
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Article
A measurement of the B d 0 oscillation frequency using leptons and D*± mesons
Data collected with the OPAL detector during 1990–1994 are used to measure the time dependence of $$B_d^0 \leftrightarrow \bar B_d^0 ...
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Article
A precise measurement of the tau polarization and its forward-backward asymmetry at LEP
A measurement of theτ lepton polarization and its forward-backward asymmetry at the Z0 resonance using the OPAL detector is described. The measurement is based on analyses of τ→ρντ, ττπ(K)ντ,
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Article
Multiplicity dependence of Bose-Einstein correlations in hadronic Z0 decays
Bose-Einstein correlations between like charged track pairs have been studied using a sample of approximately 3.6 million multihadronic Z0 decays collected with the OPAL detector at LEP. The radius of the emittin...
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Article
QCD studies with e+e− annihilation data at 130 and 136 GeV
We have studied hadronic events produced at LEP at centre-of-mass energies of 130 and 136 GeV. Distributions of event shape observables, jet rates, momentum spectra and multiplicities are presented and compare...
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Article
Upper limit on theν τ mass fromτ → 3hν τ decays
A new technique has been used to determine a limit on theν τ mass using Z0→τ + τ − events selected from 140 pb−1
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Article
Search for a narrow resonance in Z0 decays into hadrons and isolated photons
A search for the hadronic decay of a hypothetical resonance S0 in the process e+e−→γ + hadrons at Z0 energies is reported. Particular care is taken to optimise the sensitivity to a scalar resonance decaying into ...
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Article
A study of charm hadron production in \(Z^0 \to c\bar c\) and \(Z^0 \to b\bar b\) decays at LEPdecays at LEP
Measurements of the production of the weakly decaying charmed hadrons: D0, D+, D s + andΛ ...
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Article
Measurement of the average b-baryon lifetime and the product branching ratio \(f(b \to \Lambda _b ) \cdot BR(\Lambda _b \to \Lambda \ell ^ - \bar vX)\)
The average lifetime of b-flavoured baryons measured with the OPAL detector is updated to include data collected between 1990 and 1994 at LEP. Bottom-flavoured baryons that decay semileptonically and produce aΛ b...
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Article
A comparison of b and uds quark jets to gluon jets
Symmetric three-jet events are selected from hadronic Z0 decays such that the two lower energy jets are each produced at an angle of about 150° with respect to the highest energy jet. In some cases, a displaced s...
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Article
A study of QCD structure constants and a measurement of \(\alpha _s (M_{Z^0 } )\) at LEP using event shape observables
The dependence of event shape cross sections on the QCD structure constantsC A ,C F andT F is studied usi...
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Article
Measurement of the leptonic branching ratios of the τ lepton
The leptonic branching ratios of the tau lepton have been determined from data collected by the OPAL detector in 1991 and 1992. From a sample of 27196 e+e−→τ+τ− candidates we find 7322
