0000000000089137

AUTHOR

Parker D

showing 3 related works from this author

Improved measurements of electroweak parameters from Z decays into fermion pairs

1992

The properties of the Z resonance are measured on the basis of 190000 Z decays into fermion pairs collected with the ALEPH detector at LEP. Assuming lepton universality, M(Z) = (91.182 +/- 0.009exp +/- 0.020L;P) GeV, GAMMA(Z) = (2484 +/- 17) MeV, sigma(had)0 = (41.44 +/- 0.36) nb, and GAMMA(had)/GAMMA(ll) = 21.00 +/- 0.20. The corresponding number of light neutrino species is 2.97 +/- 0.07. The forward-backward asymmetry in leptonic decays is used to determine the ratio of vector to axial-vector coupling constants of leptons: g(V)2(M(Z)2)/g(A)2(M(Z)2) = 0.0072 +/- 0.0027. Combining these results with ALEPH results on quark charge and bbBAR asymmetries, and tau-polarization, sin2 theta(W)(M(…

QuarkPhysicsParticle physicsPhysics and Astronomy (miscellaneous)Electron–positron annihilationHigh Energy Physics::PhenomenologyElectroweak interactionElementary particleWeinberg angleFermionALEPH detectorNuclear physicsHigh Energy Physics::ExperimentNeutrinoEngineering (miscellaneous)Particle Physics - ExperimentLepton
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Evidence for b baryons in Z decays

1992

Abstract In 160 000 hadronic Z decays recorded with the ALEPH detector at LEP, the yields of Λl− and Λl+ combinations have been measured. The observed excess of Λl− over Λl+ of 53±13 is interpreted as evidence for b baryons and their semileptonic decay. Assuming that three body decay processes such as Λ b →Λ c + l − v dominate the semileptonic decay of b baryons, this ex cess corresponds to a product branching ratio BR ( b →Λ b )· BR (Λ b →Λ c + l − v )· BR (Λ c + →ΛX) = (0.95±0.22 ( stat. )±0.21( syst. ))% , where Λb and Λc+ denote the bottom and charm baryons respectively.

Semileptonic decayPhysicsNuclear and High Energy PhysicsParticle physicsBranching fractionPhysicsElectron–positron annihilationHigh Energy Physics::PhenomenologyHadronNuclear physicsBaryonHigh Energy Physics::ExperimentCharm (quantum number)Nuclear ExperimentParticle Physics - Experiment
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AN INVESTIGATION INTO INTERMITTENCY

1992

The results of an investigation based on ALEPH data, e+ e- --> hadrons at square-root s = 91 GeV, into fluctuations in rapidity space are presented. It is found that the behaviour of the factorial moments is well represented by the Lund parton shower model. An estimate is made of the scale of fluctuations needed to describe the data. Differential moments are introduced and are used to demonstrate that within the average represented by the traditional factorial moments the pattern of fluctu10.1007/BF01483869ations is itself a strong function of rapidity. This pattern is shown to be primarily associated with the emission of hard gluons. The implied structure between the hadron clusters and pa…

PhysicsParticle physicsPhysics and Astronomy (miscellaneous)RANGEHadronPartonElementary particleDECAYSGluonMoment (physics)Transverse massRapidityHigh Energy Physics::ExperimentParton showerANNIHILATIONNuclear ExperimentEngineering (miscellaneous)Particle Physics - Experiment
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