Showing papers by "Laurent Duflot published in 1993"
TL;DR: In this article, a variable is constructed for each τ decay channel which carries all the available information on the τ spin state, and its use allows a simple determination of the polarization with the maximal sensitivity for all final states.
175 citations
TL;DR: In this paper, a measurement of the partial width ratio using a method which tags the decays through the lifetimes of the produced heavy hadrons is presented, which relies on the tracking precision afforded by a double-sided silicon vertex detector.
128 citations
TL;DR: In this paper, a data sample corresponding to about 1 233 000 hadronic Z decays collected by the ALEPH experiment at LEP was used to search for the standard model Higgs boson.
92 citations
TL;DR: In this paper, a data sample corresponding to 1.23 million hadronic Z decays collected by the ALEPH detector at LEP has been searched for signals of the production of a non-minimal CP-even Higgs boson h in the reaction e + e − → hZ ∗.
68 citations
TL;DR: In this paper, the strong coupling constant of the τ lepton was determined from the leptonic branching ratios, the lifetime, and the invariant mass distribution of the hadronic lepton.
64 citations
TL;DR: In this paper, an analysis of γγ interactions using untagged hadronic data obtained by the ALEPH detector at LEP is performed using a model based on the vector meson dominance mechinism (VDM).
55 citations
TL;DR: This paper presents national plans on referencing and archiving doctoral theses coordinated by the government as well as some initiatives for creating full text archives.
43 citations
TL;DR: In this article, the lifetime of B 0 and B − mesons is estimated from the measured decay length and the momentum and mass of the D -lepton system, and a fit to the proper time of 77 D ∗+ l − and 77 D 0 l − candidates, combined with a constraint on the lifetime ratio ( τ − τ 0 ) arising from the relative rates of observed D − and D − events, yielded the following lifetimes: τ 0 =1.52 −0.18 +0.20 ( stat.
36 citations
TL;DR: In this article, the ALEPH detector at LEP has been used to estimate the resonance parameters of the neutrino Z. The forward-backward asymmetry in lepton-pair decays is used to determine the ratio of vector to axial-vector couplings of leptons.
Abstract: Based on 520 000 fermion pairs accumulated during the first three years of data collection by the ALEPH detector at LEP, updated values of the resonance parameters of theZ are determined to beMZ=(91.187±0.009) GeV, ΓZ=(2.501±0.012) GeV, σhad0=(41.60±0.27) nb, andRl=20.78±0.13. The corresponding number of light neutrino species isNν=2.97±0.05. The forward-backward asymmetry in lepton-pair decays is used to determine the ratio of vector to axial-vector couplings of leptons:gV2(MZ2)/gA2(MZ2)=0.0052±0.0016. Combining this with ALEPH measurements of theb andc quark asymmetries and τ polarization gives sin2θWeff=0.2326±0.0013. Assuming the minimal Standard Model, and including measurements ofMW/MZ fromp\(\bar p\) colliders and neutrino-nucleon scattering, the mass of the top quark is\(M_{top} = 156 \pm \begin{array}{*{20}c} {22} \\ {25} \\ \end{array} \pm \begin{array}{*{20}c} {17} \\ {22Higgs} \\ \end{array} \) GeV.
26 citations
TL;DR: In this paper, the branching fraction of Z → b b relative to all hadronic decays of the Z has been measured using event shape variables to preferentially select Z→ b b events.
26 citations
TL;DR: In a sample of about 1.1 million hadronic Z decays recorded with the ALEPH detector during the 1990-1992 running of LEP, two unambiguous BS meson candidates were observed as discussed by the authors.
TL;DR: The mass limits for the pair production of fractionally charged particles and of heavy, long-lived charged particles are extended to 43 GeV/c2 at 90% confidence level in this article.
TL;DR: In this article, the authors measured the tau polarisation in the decay modes τ→ev\(\bar v\), τ→μv\(bar v)), τ→πν,τ→ρν and τ→a1ν using both the individual tau decay kinematics and the event acollinearity.
Abstract: Using 18.8 pb−1 of data collected in 1990 and 1991, ALEPH has measured the tau polarisation in the decay modes τ→ev\(\bar v\), τ→μv\(\bar v\), τ→πν, τ→ρν and τ→a1ν, using both the individual tau decay kinematics and the event acollinearity. The measurement of the tau polarisation as a function of the production polar angle yields the two parametersAτ andAe, whereAl=2gvlgAl/(gvl)2+(gAl)2] The resultsAτ=0.143±0.023 andAe=0.120±0.026 are consistent with the hypothesis of electron-tau universality. Assuming universality yields a measurement of the effective weak mixing angle sin2θweff=0.2332±0.0022.
TL;DR: A measurement of the average lifetime of b hadrons has been performed with dipole method on a sample of 260 000 hadronic Z decays recorded with the ALEPH detector during 1991 as mentioned in this paper.
TL;DR: In this article, four-fermion contact term models were fitted to the lepton data and lower limits on the energy scale Λ of such terms were set at 95% c.l.
Abstract: Contact interactions are searched for using the differential cross sections for the reactionse+e−→e+e−,e+e−→µ+µ−,e+e−→τ+τ− ande+e−→γγ measured at 12 energies around theZ peak and corresponding to about 20 pb−1 of cumulated luminosity. Four-fermion contact term models assuming various chiralities of lepton currents are fitted to the lepton data and lower limits on the energy scale Λ of such terms are set at 95% c.l. The limits vary in the range 0.9–4.7 TeV, depending on the model and on the lepton flavour. Theeeγγ contact terms are searched for assuming various chiralities. Limits on the energy scale Λ between 79 and 130 GeV are extracted from the data. The results are compared and combined with those reported at lower energies.
TL;DR: In this article, a search for high mass photon pairs from the processes e + e − → f f γγ (f = e, μ, τ, v and q) with the ALEPH detector is reported.