40 research outputs found

    Angular correlations in three-jet events in ep collisions at HERA

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    Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of 127 pb-1. Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the final state and the proton-beam direction. These correlations provide a stringent test of perturbative QCD and show sensitivity to the contributions from different colour configurations. Fixed-order perturbative QCD calculations assuming the values of the colour factors C_F, C_A and T_F as derived from a variety of gauge groups were compared to the measurements to study the underlying gauge group symmetry. The measured angular correlations in the deep inelastic ep scattering and photoproduction regimes are consistent with the admixture of colour configurations as predicted by SU(3) and disfavour other symmetry groups, such as SU(N) in the limit of large N.Comment: 48 pages, 19 figure

    Angular correlations in three-jet events in epep collisions at HERA

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    A QCD Analysis of ZEUS Diffractive Data

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    Diffractive Photoproduction of Dijets in {\it ep} Collisions at HERA

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    Energy Dependence of the Charged Multiplicity in Deep Inelastic Scattering at HERA

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    K0SK0S\mathrm{K0_{S}K0_{S}} resonance production in epep collisions at HERA

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    Inclusive K0SK0S production in ep collisions at HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb-1. Enhancements in the mass spectrum were observed and are attributed to the production of f2(1270)/a02(1320), f'2(1525) and f0(1710). Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments, and are consistent with the PDG values. The f0(1710) state, which has a mass consistent with a glueball candidate, was observed with a statistical significance of 5 standard deviations. However, if this state is the same as that seen in gamma gamma -> K0SK0S, it is unlikely to be a pure glueball state.Comment: 10 pages, 3 figures, 1 tabl

    Multi-jet cross sections in charged current e±p\mathrm{e^{\pm}p} scattering at HERA

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    Measurement of J/ψ\psi helicity distributions in inelastic photoproduction at HERA

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    Beauty photoproduction using decays into electrons at HERA

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    High-{\it ETE_{T}} dijet photoproduction at HERA

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    We discuss properties of hypothetical scale invariant (unparticle) matter by viewing it as a tower of massive particles. We show how peculiar properties of unparticles emerge in the limit when the mass spacing parameter Delta vanishes. We explain why unparticle cannot decay in this limit and how, for finite Delta, the decays manifest themselves in a relation between the reconstructed invariant mass and vertex displacement. We describe a model field theory in AdS5 which explicitly implements the deconstruction procedure by truncating the extra dimension to size of order 1/Delta.Comment: 5 page
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