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A search has been performed for the Standard Model Higgs boson in the data sample collected with the ALEPH detector at LEP, at centre-of-mass energies up to 209 GeV. An excess of 3 σ beyond the background expectation is found, consistent with the production of the Higgs boson with a mass near 114 GeV/c 2. Much of this excess is seen in the four-jet(More)
The cross sections and forward-backward asymmetries of hadronic and leptonic events produced in e + e − collisions at centre-of-mass energies from 130 to 183 GeV are presented. Results for e + e − , µ + µ − , τ + τ − , q¯ q, b ¯ b and c¯ c production show no significant deviation from the Standard Model predictions. This enables constraints to be set upon(More)
This study examined the sources of error involved in geocoding, by systematically evaluating the strengths and weaknesses of three widely used tools for geocoding. We tested them against a random sample of addresses from a state administrative address master file and found considerable variation in identification of census block geocodes of addresses. This(More)
The rate of gluon splitting into c¯ c pairs in hadronic Z decays is measured using the data sample collected by ALEPH from 1991 to 1995. The selection is based on the identification of leptons (electrons and muons) originating from semileptonic charm decays, and on the topological properties of signal events. The result derived from the selected sample is g(More)
Hadronic Z decays into three jets are used to test QCD models of colour reconnection (CR). A sensitive quantity is the rate of gluon jets with a gap in the particle rapidity distribution and zero jet charge. Gluon jets are identified by either energy-ordering or by tagging two b-jets. The rates predicted by two string-based tunable CR models, one(More)
Hadronic Z decay data taken with the ALEPH detector at LEP1 are used to measure the three-jet rate as well as moments of various event-shape variables. The ratios of the observables obtained from b-tagged events and from an inclusive sample are determined. The mass of the b quark is extracted from a fit to the measured ratios using a next-to-leading order(More)
Search for γγ decays of a Higgs boson produced in association with a fermion pair in e + e − collisions at LEP The ALEPH Collaboration 1) Abstract A search for γγ decays of a Higgs boson is performed in the data sample collected at LEP with the ALEPH detector between 1991 and 1999. This corresponds to an integrated luminosity of 672 pb −1 at centre-of-mass(More)
Indirect limits on the mass of the lightest neutralino are derived from the results of searches for charginos, neutralinos, and sleptons performed with data taken by the ALEPH Collaboration at centre-of-mass energies near the Z peak and at 130 and 136 GeV. Within the context of the Minimal Supersymmetric Standard Model and when M ˜ ν ≥ 200 GeV/c 2 , the(More)