898 research outputs found

    Observation of Scaling Violations in Scaled Momentum Distributions at HERA

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    Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of xx and Q2Q^2 using the ZEUS detector. The evolution of the scaled momentum, xpx_p, with Q2,Q^2, in the range 10 to 1280 GeV2GeV^2, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of Q2Q^2.Comment: 21 pages including 4 figures, to be published in Physics Letters B. Two references adde

    The Theory of the Nucleon Spin

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    I discuss two topics of current interest in the study of the spin structure of the nucleon. First, I discuss whether there is a sum rule for the components of the nucleon's angular moments. Second, I discuss the measurement of the nucleon's transversity distribution in light of recent results reported by the HERMES collaboration at DESY.Comment: 15 pages, 8 figures, LaTeX using rspublic.cls and BoxedEPS macros; as submitted to Phil Trans A of the Royal Society for forthcoming volume: The Quark Structure of Matter; email correspondence to [email protected]

    QCD and Hadron Dynamics

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    Perturbative QCD predicts and describes various features of multihadron production. An amazing similarity between observable hadron systems and calculable underlying parton ensembles justifies the attempts to use the language of quarks and gluons down to small momentum scales, to approach the profound problems that are commonly viewed as being entirely non-perturbative.Comment: Talk at the Royal Society meeting "Structure of Matter", London, May 200

    Photon Structure and Quantum Fluctuation

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    Photon structure derives from quantum fluctuation in quantum field theory to fermion and anti-fermion, and has been an experimentally established feature of electrodynamics since the discovery of the positron. In hadronic physics, the observation of factorisable photon structure is similarly a fundamental test of the quantum field theory Quantum Chromodynamics (QCD). An overview of measurements of hadronic photon structure in e+e- and ep interactions is presented, and comparison made with theoretical expectation, drawing on the essential features of photon fluctuation into quark and anti-quark in QCD.Comment: 29 pages, 15 figures, to appear in Philosophical Transactions of the Royal Society of London (Series A: Mathematical, Physical and Engineering Sciences

    Effect of exotic S=+1 resonances on KL0pK^0_L p scattering data

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    We consider the effect of an exotic S=+1 Θ+\Theta^+ resonance on the scattering of neutral kaons off protons. Explicit results are presented for the KL0pK^0_L p total cross sections.Comment: 2 pages, 3 figure

    The Study of Two-dimensional Polytropic Stars

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    In this article we have studied the structure of hypothetical two-dimensional polytropic stars. Considering some academic interest, we have developed a formalism to investigate some of the gross properties of such stellar objects. However, we strongly believe that the formalism developed here may be prescribed as class problem for post-graduate level students in physics or a post-graduate dissertation project work in physics.Comment: 4 pages LATEX file, No Figure, To appear in "The Scientific Voyage Journal

    The performance of farm animal assessment

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    This paper argues that the current drive towards greater use of animal-based measures for welfare assessment raises important issues for how farm visits by welfare assessors are performed. As social scientists, we employ a number of contemporary social science ideas to offer a new approach to examining the practice and performance of farm animal assessment. We identify key findings from a recent study of contemporary farm assessment and speculate upon what some of the challenges of introducing animal-based measures may be. We conclude by arguing for a greater awareness of how sets of knowledge are made, circulated, practiced and become an integral component of the procedures, practices and discourses around farm animal welfare assessment in farm assuranc
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