8,432 research outputs found

    A momentum Space Analysis of the Triple Pomeron Vertex in pQCD

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    We study properties of the momentum space Triple Pomeron Vertex in perturbative QCD. Particular attention is given to the collinear limit where transverse momenta on one side of the vertex are much larger than on the other side. We also comment on the kernels in nonlinear evolution equations.Comment: Minor misprints corrected. To be published in EPJ

    QCD Corrections to Electroweak Vector Boson Scattering at Small Scattering Angles

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    We investigate the role of a certain class of QCD corrections to electroweak vector boson scattering at small scattering angles and large energies. These are present since, from the perturbative analysis, the vector bosons may dissociate into quark-antiquark pairs giving rise to colour dipoles interacting through gluon exchanges. After the computation of the vector boson impact factors, we present expressions for the lowest order QCD scattering amplitude and for the leading logarithmic BFKL amplitude. Particularly we discuss numerical results for the process γγZZ\gamma\gamma\to ZZ. The QCD corrections to the cross section resulting from the interference with the electroweak ones are estimated and compared with the leading pure electroweak part. Corrections resulting from the leading log BFKL amplitude are of the order of few percent already at the 0.510.5 - 1 TeV energy range.Comment: 21 pages,9 figures, discussion on the helicity-flip impact factors added, typos correcte

    The Pomeranchuk Singularity and Vector Boson Reggeization in Electroweak Theory

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    We investigate the high energy behaviour of vector boson scattering in the electroweak sector of the standard model. In analogy with the BFKL analysis in QCD we compute production amplitudes in the multi-Regge limit and derive, for the vacuum exchange channel, the integral equation for vector particle scattering. We also derive and solve the bootstrap equations for the isospin-1 exchange channel, both for the reggeizing charged and non-reggeizing neutral vector bosons.Comment: 31 pages, 12 figures, 1 tabl

    An Analytical Expression for the Non-Singlet Structure Functions at Small xx in the Double Logarithmic Approximation

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    A simple analytic expression for the non-singlet structure function fNSf_{NS} is given. The expression is derived from the result of Ref. [1] obtained by low xx resummation of the quark ladder diagrams in the double logarithmic approximation of perturbative QCD.Comment: 5 pages, A few comments and refs are adde

    The new course at Muresk Agricultural College

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    THE original aim of all the agricultural colleges in Australia was to train young men to be farmers. Over the years, and particularly in recent years, the colleges in the Eastern States found that less and less of their students were coming from the farming community, and a diminishing number were returning to farming

    Performance Enhancement of the Flexible Transonic Truss-Braced Wing Aircraft Using Variable-Camber Continuous Trailing-Edge Flaps

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    Aircraft designers are to a growing extent using vehicle flexibility to optimize performance with objectives such as gust load alleviation and drag minimization. More complex aerodynamically optimized configurations may also require dynamic loads and perhaps eventually flutter suppression. This paper considers an aerodynamically optimized truss-braced wing aircraft designed for a Mach 0.745 cruise. The variable camber continuous trailing edge flap concept with a feedback control system is used to enhance aeroelastic stability. A linearized reduced order aerodynamic model is developed from unsteady Reynolds averaged Navier-Stokes simulations. A static output feedback controller is developed from that model. Closed-loop simulations using the reduced order aerodynamic model show that the controller is effective in stabilizing the vehicle dynamics

    The Small-x Behaviour of the Singlet Polarized Structure Function g_2 in the Double Logarithmic Approximation

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    The small-x behavior of the singlet contributions to the polarized structure function g_2(x,Q^2) is calculated in the double-logarithmic approximation of perturbative QCD. The dominant contribution is due to the gluons which, in contrast to the unpolarized case, mix with the fermions also in the small-x domain. We find a power-like growth in 1/x in the odd-signature parts of the amplitude with the same power as in the singlet function g_1(x,Q^2) at x<< 1.Comment: 20 pages, latex, 3 ps figure

    The Dynamics of Spatial Labor Mobility in The Netherlands

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    The spatial mobility of labor changes over time. Both the general propensity to migrate and the spatial allocation of mobile people over regions of destination are characterized by important dynamic properties. This paper discusses several factors that may explain these dynamic properties of internal labor migration. We focus especially on the influence of labor market and housing conditions on the mobility of people. A two-stage, generation-allocation model is proposed, to investigate the role of different factors in the explanation of aggregate interregional migration flows. This model is applied to recent data on interprovincial labor migration in the Netherlands. The results indicate that housing supply seems to be an important determinant of temporal developments of spatial mobility, and also that the conditions of national and regional labor markets are associated with specific properties of recent migration patterns
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