763 research outputs found

    Enhanced nonperturbative effects in jet distributions

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    We consider the triple differential distribution d\Gamma/(dE_J)(dm_J^2)(d\Omega_J) for two-jet events at center of mass energy M, smeared over the endpoint region m_J^2 << M^2, |2 E_J -M| ~ \Delta, \lqcd << \Delta << M. The leading nonperturbative correction, suppressed by \lqcd/\Delta, is given by the matrix element of a single operator. A similar analysis is performed for three jet events, and the generalization to any number of jets is discussed. At order \lqcd/\Delta, non-perturbative effects in four or more jet events are completely determined in terms of two matrix elements which can be measured in two and three jet events.Comment: Significant changes made. The first moment does not vanish--the paper has been modified to reflect this. Relations between different numbers of jets still hol

    An operator expansion for the elastic limit

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    A leading twist expansion in terms of bi-local operators is proposed for the structure functions of deeply inelastic scattering near the elastic limit x1x \to 1, which is also applicable to a range of other processes. Operators of increasing dimensions contribute to logarithmically enhanced terms which are supressed by corresponding powers of 1x1-x. For the longitudinal structure function, in moment (NN) space, all the logarithmic contributions of order lnkN/N\ln^k N/N are shown to be resummable in terms of the anomalous dimension of the leading operator in the expansion.Comment: 9 pages, 1 figure, uses REVTEX 3.1 and axodra

    Dijet Event Shapes as Diagnostic Tools

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    Event shapes have long been used to extract information about hadronic final states and the properties of QCD, such as particle spin and the running coupling. Recently, a family of event shapes, the angularities, has been introduced that depends on a continuous parameter. This additional parameter-dependence further extends the versatility of event shapes. It provides a handle on nonperturbative power corrections, on non-global logarithms, and on the flow of color in the final state.Comment: 18 pages, 3 figure

    Summary: Working Group on QCD and Strong Interactions

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    In this summary of the considerations of the QCD working group at Snowmass 2001, the roles of quantum chromodynamics in the Standard Model and in the search for new physics are reviewed, with empahsis on frontier areas in the field. We discuss the importance of, and prospects for, precision QCD in perturbative and lattice calculations. We describe new ideas in the analysis of parton distribution functions and jet structure, and review progress in small-xx and in polarization.Comment: Snowmass 2001. Revtex4, 34 pages, 4 figures, revised to include additional references on jets and lattice QC

    The Perturbative Pole Mass in QCD

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    It is widely believed that the pole mass of a quark is infrared-finite and gauge-independent to all orders in perturbation theory. This seems not to have been proved in the literature. A proof is provided here.Comment: 12 pages REVTeX with 2 figures; archiving published version with note and references added. If you thought this was proven long ago see http://www-theory.fnal.gov/people/ask/TeX/mPole

    Large distance behaviour of light cone operator product in perturbative and nonperturbative QCD regimes

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    We evaluate the coordinate space dependence of the matrix elements of the commutator of the electromagnetic and gluon currents in the vicinity of the light-cone but at large distances within the parton model, DGLAP, the resummation approaches to the small x behaviour of DIS processes, and for the Unitarity Bound. We find that an increase of the commutator with relative distance pypy as (py)f(py,y2=t2r2)\propto (py)f(py,y^2=t^2-r^2) is the generic property of QCD at small but fixed space-time interval y2=t2r2y^2=t^2-r^2 in perturbative and nonperturbative QCD regimes. We explain that the factor pypy follows within the dipole model (QCD factorization theorem) from the properties of Lorents transformation. The increase of f(r)f(r) disappeares at central impact parameters if cross section of DIS may achieve the Unitarity Limit. We argue that such long range forces are hardly consistent with thermodynamic equilibrium while a Unitarity Limit may signal equilibration. Possible implications of this new long range interaction are briefly discussed.Comment: 23 page

    Two-Loop Calculations with Vertex Corrections in the Walecka Model

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    Two-loop corrections with scalar and vector form factors are calculated for nuclear matter in the Walecka model. The on-shell form factors are derived from vertex corrections within the framework of the model and are highly damped at large spacelike momenta. The two-loop corrections are evaluated first by using the one-loop parameters and mean fields and then by refitting the total energy/baryon to empirical nuclear matter saturation properties. The modified two-loop corrections are significantly smaller than those computed with bare vertices. Contributions from the anomalous isoscalar form factor of the nucleon are included for the first time. The effects of the implicit density dependence of the form factors, which arise from the shift in the baryon mass, are also considered. Finally, necessary extensions of these calculations are discussed.Comment: 29 pages in REVTeX, 18 figures, preprint IU/NTC 94-02 //OSU--94-11

    A Modeling Framework to Assess Strategies Alignment based on Collaborative Network Emotions

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    [DE] The Collaborative Networks (CN) discipline has been largely studied in last decades, addressing different problems and proposing solutions for the robust establishment of collaborative processes, within the enterprises willing to collaborate. The main aim of CN research is, therefore, to generate approaches that enable creating effective relationships in the long term, to achieve stable and agile alliances. The concept of alignment among the CN partners has been considered since the beginning of CN research. Nevertheless, novel perspectives of study in CN, such as the consideration of collaborative emotional states, within the CN, have been introduced in recent years. This paper connects the research area of strategies alignment and the CN emotion models. Accordingly, a modelling framework to assess strategies alignment considering the emotional environment within the CN is proposed. The modelling framework allows representing how the enterprises emotions affect in the selection and alignment of formulated enterprises¿ strategiesAndres, B.; Ferrada, F.; Poler, R.; Camarinha-Matos, L. (2018). A Modeling Framework to Assess Strategies Alignment based on Collaborative Network Emotions. IFIP Advances in Information and Communication Technology. 534:349-361. https://doi.org/10.1007/978-3-319-99127-6_30S349361534Camarinha-Matos, L.M.: Collaborative networks in industry and the role of PRO-VE. Int. J. Prod. Manag. Eng. 2(2), 53–57 (2014)Andres, B., Poler, R.: Models, guidelines and tools for the integration of collaborative processes in non-hierarchical manufacturing networks: a review. Int. J. Comput. Integr. Manuf. 2(29), 166–201 (2016)Bititci, U., Martinez, V., Albores, P., Parung, J.: Creating and managing value in collaborative networks. Int. J. Phys. Distrib. Logist. 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    Scaling Rule for Nonperturbative Radiation in a Class of Event Shapes

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    We discuss nonperturbative radiation for a recently introduced class of infrared safe event shape weights, which describe the narrow-jet limit. Starting from next-to-leading logarithmic (NLL) resummation, we derive an approximate scaling rule that relates the nonperturbative shape functions for these weights to the shape function for the thrust. We argue that the scaling reflects the boost invariance implicit in NLL resummation, and discuss its limitations. In the absence of data analysis for the new event shapes, we compare these predictions to the output of the event generator PYTHIA.Comment: 23 pages, 3 figures, uses JHEP3.cls (included); v2 - version to appear in JHE
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