Search for single-top production in ep collisions at HERA
Physics Letters B 559 (2003) 153-170
Measurement of subjet multiplicities in neutral current deep inelastic scattering at HERA and determination of αs
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 558:1-2 (2003) 41-58
Abstract:
The subjet multiplicity has been measured in neutral current e+p interactions at Q2 > 125 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb-1. Jets were identified in the laboratory frame using the longitudinally invariant kT cluster algorithm. The number of jet-like substructures within jets, known as the subjet multiplicity, is defined as the number of clusters resolved in a jet by reapplying the jet algorithm at a smaller resolution scale ycut. Measurements of the mean subjet multiplicity, (nsbj), for jets with transverse energies ET,jet > 15 GeV are presented. Next-to-leading-order perturbative QCD calculations describe the measurements well. The value of αs(MZ), determined from (nsbj) at ycut = 10-2 for jets with 25 < ET,jet < 71 GeV, is αs(MZ) = 0.1187 ± 0.0017(stat.)-0.0009+0.0024(syst.) -0.0076+0.0093(th.). © 2003 Published by Elsevier Science B.V.Observation of the strange sea in the proton via inclusive φ-meson production in neutral current deep inelastic scattering at HERA
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 553:3-4 (2003) 141-158
Abstract:
Inclusive φ(1020)-meson production in neutral current deep inelastic e+p scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 45 pb-1. The φ mesons were studied in the range 10 < Q2 < 100 GeV2, where Q2 is the virtuality of the exchanged photon, and in restricted kinematic regions in the transverse momentum, pT, pseudorapidity, η, and the scaled momentum in the Breit frame, xp. Monte Carlo models with the strangeness-suppression factor as determined by analyses of e+e- annihilation events overestimate the cross sections. A smaller value of the strangeness-suppression factor reduces the predicted cross sections, but fails to reproduce the shapes of the measured differential cross sections. High-momentum φ mesons in the current region of the Breit frame give the first direct evidence for the strange sea in the proton at low x. © 2002 Published by Elsevier Science B.V.Study of the azimuthal asymmetry of jets in neutral current deep inelastic scattering at HERA
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 551:3-4 (2003) 226-240
Abstract:
The azimuthal distribution of jets produced in the Breit frame in high-Q2 deep inelastic e+p scattering has been studied with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb-1. The measured azimuthal distribution shows a structure that is well described by next-to-leading-order QCD predictions over the Q2 range considered, Q2 > 125 GeV2. © 2002 Elsevier Science B.V. All rights reserved.Search for resonance decays to lepton plus jet at DESY HERA and limits on leptoquarks -: art. no. 052004
PHYSICAL REVIEW D 68:5 (2003) ARTN 052004