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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)
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)
 The authors would like to thank the European Agency for Reconstruction for access to their data and their kind support. ABSTRACT Different procurement decisions taken by relief organizations can result in considerably different implications in regards to transport, storage, and distribution of humanitarian aid and ultimately can influence the performance(More)
The four-jet nal state is analyzed to search for hadronic decays of pair-produced heavy particles. The analysis uses the ALEPH data collected at LEP in November 1995 at centre-of-mass energies of 130 and 136 GeV, corresponding to a total integrated luminosity of 5.7 pb ?1. An excess of four-jet events is observed with respect to the standard model(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)
The production rates of D + c / ¯ Λ − c in Z → c¯ c decays are measured using the LEP I data sample recorded by the ALEPH detector. The fractional energy spectrum of the D * ± is well described as the sum of three contributions: charm hadronisation, b hadron decays and gluon splitting into a pair of heavy quarks. The probability for a c quark to hadronise(More)
A lower limit is set on the B 0 s meson oscillation parameter m s using data collected from 1991 to 1994 by the ALEPH detector. Events with a high transverse momentum lepton and a reconstructed secondary vertex are used. The high transverse momentum leptons are produced mainly by b hadron decays, and the sign of the lepton indicates the(More)
Four-fermion events have been selected in a data sample of 5.8 pb ?1 collected with the aleph detector at centre-of-mass energies of 130 and 136 GeV. The nal states`+`? q q, ` + ` ? ` + ` ? , q q, and`+`? have been examined. Five events are observed in the data, in agreement with the Standard Model predictions of 6:67 0:38 events from four-fermion processes(More)