A measurement of the lifetime of the tau lepton
Physics Letters B Elsevier 267:3 (1991) 422-430
Charged particle multiplicity distributions in restricted rapidity intervals in Z0 hadronic decays
Zeitschrift für Physik C Particles and Fields 52:2 (1991) 271-281
Abstract:
The multiplicity distributions of charged particles in restricted rapidity intervals in Z0 hadronic decays measured by the DELPHI detector are presented. The data reveal a shoulder structure, best visible for intervals of intermediate size, i.e. for rapidity limits around ±1.5. The whole set of distributions including the shoulder structure is reproduced by the Lund Parton Shower model. The structure is found to be due to important contributions from 3-and 4-jet events with a hard gluon jet. A different model, based on the concept of independently produced groups of particles, "clans", fluctuating both in number per event and particle content per clan, has also been used to analyse the present data. The results show that for each interval of rapidity the average number of clans per event is approximately the same as at lower energies. © 1991 Springer-Verlag.Charged particle multiplicity distributions in Z0 hadronic decays
Zeitschrift für Physik C Particles and Fields 50:2 (1991) 185-194
Abstract:
This paper presents an analysis of the multiplicity distributions of charged particles produced in Z0 hadronic decays in the DELPHI detector. It is based on a sample of 25364 events. The average multiplicity isA study of the reaction e+e- → μ+μ- around the Z0 pole
Physics Letters B 260:1-2 (1991) 240-248
Abstract:
Measurements of the cross section and forward-backward asymmetry for the reaction e+e- → μ+μ- using the DELPHI detector at LEP are presented. The data come from a scan around the Z0 peak at seven centre of mass energies, giving a sample of 3858 events in the polar angle region 22° < θ < 158°. From a fit to the cross section for 43° < θ < 137°, a polar angle region for which the absolute efficiency has been determined, the square root of the product of the Z0 → e+e- and Z0 → μ+μ- partial widths is determined to be (ΓeΓμ) 1 2 = 85.0 ± 0.9(stat.) ± 0.8(syst.) MeV. From this measurement of the partial width, the value of the effective weak mixing angle is determined to be sin2(θw) = 0.2267 ± 0.0037. The ratio of the hadronic to muon pair partial widths is found to be Γh/Γμ = 19.89 ± 0.40(stat.) ± 0.19(syst.). The forward-backward asymmetry at the resonance peak energy ECMS = 91.22 GeV is found to be AFB = 0.028 ± 0.020(stat.) ± 0.005(syst.). From a combined fit to the cross section and forward-backward asymmetry data, the products of the electron and muon vector and axial-vector coupling constants are determined to be VeVμ = 0.0024 ± 0.0015(stat.) ± 0.0004(syst.) and AeAμ = 0.253 ± 0.003(stat.) ± 0.003 (syst.). The results are in good agreement with the expectations of the minimal standard model. © 1991.Search for low mass Higgs bosons produced in Z0 decays
Zeitschrift für Physik C Particles and Fields 51:1 (1991) 25-35