Search
Results
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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 -
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 -
Measurements of the strong coupling constant and the QCD colour factors using four-jet observables from hadronic Z decays
(2003)The European Physical Journal CData from e+e− annihilation into hadrons, taken with the ALEPH detector at the Z resonance, are analyzed. The four-jet rate is studied as a function of the resolution parameter and compared to next-to-leading order calculations combined with resummation of large logarithms. Angular correlations in four-jet events are measured and compared to next-to-leading order QCD predictions. With these observables two different measurements are ...Journal Article -
Search for anomalous weak dipole moments of the tau lepton
(2003)The European Physical Journal CThe anomalous weak dipole moments of the τ lepton are measured in a data sample collected by ALEPH from 1990 to 1995 corresponding to an integrated luminosity of 155 pb-1. Tau leptons produced in the reaction e+e−→τ+τ− at energies close to the Z mass are studied using their semileptonic decays to π, ρ, a1→π2π0 or a1→3π. The real and imaginary components of both the anomalous weak magnetic dipole moment and the CP-violating anomalous weak ...Journal Article