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Search for colour reconnection effects in e+e- -> W+W- -> hadrons through particle-flow studies at LEP
(2003)Physics Letters BA search for colour reconnection effects in hadronic decays of W pairs is performed with the L3 detector at centre-of-mass energies between 189 and 209 GeV. The analysis is based on the study of the particle flow between jets associated to the sameW boson and between two different W bosons in qqqq events. The ratio of particle yields in the different interjet regions is found to be sensitive to colour reconnection effects implemented in ...Journal Article -
Evolution of a synoptic-scale vortex advecting toward a high mountain
(2003)Tellus A: Dynamic Meteorology and OceanographyA model-based study is undertaken of a synoptic-scale vortex’s encounter with Greenland-scale topography. The ambient setting is a barotropic westerly flow of uniform potential vorticity. This flow is both incident upon and induces an anticyclone over the topography, and it also serves to advect the vortex toward the mountain. In a simulated evolution of the flow the vortex circumnavigates poleward around the mountain but concomitantly ...Journal Article -
Search for the Standard Model Higgs Boson at LEP
(2003)Physics Letters BThe four LEP Collaborations, ALEPH, DELPHI, L3 and OPAL, have collected a total of 2461 pb−1 of e+e− collision data at centre-of-mass energies between 189 and 209 GeV. The data are used to search for the Standard Model Higgs boson. The search results of the four Collaborations are combined and examined in a likelihood test for their consistency with two hypotheses: the background hypothesis and the signal plus background hypothesis. The ...Journal Article -
Z boson pair-production at LEP
(2003)Physics Letters BEvents stemming from the pair-production of Z bosons in e+e- collisions are studied using 217.4 pb-1 of data collected with the L3 detector at centre-of-mass energies from 200 GeV up to 209 GeV. The special case of events with b quarks is also investigated. Combining these events with those collected at lower centre-of-mass energies, the Standard Model predictions for the production mechanism are verified. In addition, limits are set on ...Journal Article -
A measurement of the gluon splitting rate into c(c)over-bar pairs in hadronic Z decays
(2003)Physics Letters BThe 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 gc ̄c = (3.26 ± 0.23(stat) ± 0.42(syst))%.Journal Article -
Single- and multi-photon production in e(+) e(-) collisions at √s up to 209 GeV
(2003)The European Physical Journal CEvents containing only energetic photons are analysed in a sample of 628pb−1 of data recorded from e+e− collisions at centre-of-mass energies between 189 and 209 GeV by the ALEPH detector at LEP. The e+e−→νν¯γ(γ) and e+e−→γγ(γ) cross sections are measured and found to be in agreement with the standard model predictions. The number of light neutrino generations is determined to be Nν=2.86±0.09. Upper limits are derived on the cross sections ...Journal Article -
Search for supersymmetric particles with R-parity violating decays in e(+)e(-) collisions at root s up to 209 GeV
(2003)The European Physical Journal CSearches for the pair production of supersymmetric particles under the assumption that R-parity is violated via a single dominant \ensuremathLLE¯, \ensuremathLQD¯ or \ensuremathU¯D¯D¯ coupling are performed using the data collected by the ALEPH detector at LEP at centre-of-mass energies from 189 to 209GeV. The numbers of observed candidate events in the data are in agreement with the Standard Model expectation, and limits on the production ...Journal Article -
Measurement of the hadronic photon structure function F-2(gamma)(x,Q(2)) in two-photon collisions at LEP
(2003)The European Physical Journal CThe hadronic photon structure function Fγ2(x,Q2) is measured from data taken with the ALEPH detector at LEP. At centre-of-mass energies between s√=189GeV and 207GeV an integrated luminosity of 548.4pb−1 is analyzed in two ranges of Q2 with ⟨Q2⟩=17.3 GeV2 and 67.2 GeV2. Detector effects and acceptance are corrected for with a Tikhonov unfolding procedure. The results are compared to theoretical predictions and measurements from other experiments.Journal Article -
Diffractive photoproduction of J/ψ mesons with large momentum transfer at HERA
(2003)Physics Letters BThe diffractive photoproduction of J/ψ mesons is measured with the H1 detector at the ep collider HERA using an integrated luminosity of 78 pb -1. The differential cross section dσ(γp → J/ψY)/dt is studied in the range 2 < |t| < 30 GeV2, where t is the square of the four-momentum transferred at the proton vertex. The cross section is also presented as a function of the photon-proton centre-of-mass energy Wγp in three t intervals, spanning ...Journal Article -
Improved search for B-S(0)-(B)over-bar(S)(0) oscillations
(2003)The European Physical Journal CAn improved search for B s 0 oscillations is performed in the ALEPH data sample collected during the first phase of LEP, and reprocessed in 1998. Three analyses based on complementary event selections are presented. First, decays of B s 0 mesons into hadronic flavour eigenstates are fully reconstructed. This selection yields a small sample of candidates with excellent decay length and momentum resolution and hi gh average B s 0 purity. ...Journal Article