Showing papers by "Achim Geiser published in 2003"
TL;DR: In this paper, the results of a next-to-leading-order QCD analysis of the ZEUS data on deep inelastic scattering together with fixed-target data were performed, from which the gluon and quark densities of the proton and the value of the strong coupling constant alpha(s)(M-Z) were extracted.
Abstract: Next-to-leading-order QCD analyses of the ZEUS data on deep inelastic scattering together with fixed-target data have been performed, from which the gluon and quark densities of the proton and the value of the strong coupling constant alpha(s)(M-Z) were extracted. The study includes a full treatment of the experimental systematic uncertainties including point-to-point correlations. The resulting uncertainties in the parton density functions are presented. A combined fit for alpha(s)(M-Z) and the gluon and quark densities yields a value for alpha(s)(M-Z) in agreement with the world average. The parton density functions derived from ZEUS data alone indicate the importance of HERA data in determining the sea quark and gluon distributions at low x. The limits of applicability of the theoretical formalism have been explored by comparing the fit predictions to ZEUS data at very low Q(2).
187 citations
TL;DR: In this paper, the results of a search for vμ → v e oscillations in the NOMAD experiment at CERN were presented and the 90% confidence limits obtained are Δm2 < 0.4 eV 2 for maximal mixing and sin2(2θ) < 1.4 × 10-3 for large Δm 2.
184 citations
TL;DR: In this article, a search for single-top production via flavour changing neutral current transitions involving a neutral electroweak vector boson, γ or Z, was performed with the ZEUS detector at HERA using data corresponding to an integrated luminosity of 0.37 fb − 1.
84 citations
11 Dec 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a method for the calculation of the flux and composition of the West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations is described.
Abstract: The method developed for the calculation of the flux and composition of the West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations is described. The calculation is based on particle production rates computed using a recent version of FLUKA and modified to take into account the cross sections measured by the SPY and NA20 experiments. These particles are propagated through the beam line taking into account the material and magnetic fields they traverse.The neutrinos produced through their decays are tracked to the NOMAD detector.
61 citations
TL;DR: In this paper, the subjet multiplicity has been measured in neutral current e{sup +} p interactions at Q(2) gt 125 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb{sup -1}.
32 citations
TL;DR: In this paper, the authors measured φ mesons in the range 10 Q 2 2, where Q 2 is the virtuality of the exchanged photon, and in restricted kinematic regions in the transverse momentum, p T, pseudorapidity, η, and scaled momentum in the Breit frame, x p.
10 citations