493 research outputs found

    Non-Perturbative Scales in Soft Hadronic Collisions at High Energies

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    We investigate the role of nonperturbative quark-gluon dynamics in soft high energy processes. In order to reproduce differential and total cross sections for elastic proton-proton and proton-antiproton-scattering at high energy and small momentum transfer it turns out that we need two scales, the gluonic correlation length and a confinement scale. We find a small gluonic correlation length, a = 0.2 fm, in accordance with recent lattice QCD results.Comment: 8 pages,latex, 2 figures uuencode

    Odd C-P contributions to diffractive processes

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    We investigate contributions to diffractive scattering, which are odd under C- and P-parity. Comparison of p-pˉ\bar p and p-p scattering indicates that these odderon contributions are very small and we show how a diquark clustering in the proton can explain this effect. A good probe for the odderon exchange is the photo- and electroproduction of pseudo-scalar mesons. We concentrate on the pi^0 and show that the quasi elastic pi^0-production is again strongly suppressed for a diquark structure of the proton whereas the cross sections for diffractive proton dissociation are larger by orders of magnitude and rather independent of the proton structure.Comment: 18 pages, LaTex2e, graphicx package, 14 eps figures include

    Eikonal profile functions and amplitudes for pp\rm pp and pˉp\bar{\rm p}{\rm p} scattering

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    The eikonal profile function J(b)J(b) obtained from the Model of the Stochastic Vacuum is parametrized in a form suitable for comparison with experiment. The amplitude and the extended profile function (including imaginary and real parts) are determined directly from the complete pp and pˉ\bar{\rm p}p elastic scattering data at high energies. Full and accurate representation of the data is presented, with smooth energy dependence of all parameters. The changes needed in the original profile function required for description of scattering beyond the forward direction are described.Comment: Latex, 28 pages and 16 figure

    Not quite the 'Great Britain of the Far East': Japan's security, the US-Japan alliance and the 'war on terror' in East Asia

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    Japan, in responding to US expectations for support in the 'war on terror', has displayed a degree of strategic convergence on global security objectives, thus prompting policy-makers and observers to dub it the 'Great Britain of the Far East'. This article argues, however, that Japan is far from assuming this role. For Japan, the 'war on terror' serves more as a political pretext for legitimating long-planned changes in military security policy that are often only marginally related to the US's anti-terrorism agenda. Instead, Japan has focused much more on using the terror threat rationale as a means to push forward its response to the regional and traditional security challenges of North Korea and China, even if at times it attempts to depict both as 'new security challenges' or as involving elements of counterterrorism. The final conclusion is that US military hegemony may be weakened by Japan's and the Asia-Pacific's potential divergence from the US global security agenda

    Heisenberg's Universal (lns)**2 Increase of Total Cross Sections

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    The (lns)**2 behaviour of total cross-sections, first obtained by Heisenberg 50 years ago, receives now increased interest both on phenomenological and theoretical levels. In this paper we present a modification of the Heisenberg's model in connection with the presence of glueballs and we show that it leads to a realistic description of all existing hadron total cross-section data.Comment: 6 pages, 3 figure

    X-Ray Scattering at FeCo(001) Surfaces and the Crossover between Ordinary and Normal Transitions

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    In a recent experiment by Krimmel et al. [PRL 78, 3880 (1997)], the critical behavior of FeCo near a (001) surface was studied by x-ray scattering. Here the experimental data are reanalyzed, taking into account recent theoretical results on order-parameter profiles in the crossover regime between ordinary and normal transitions. Excellent agreement between theoretical expectations and the experimental results is found.Comment: 9 pages, Latex, 1 PostScript figure, to be published in Phys.Rev.

    Analytic Solution of Emden-Fowler Equation and Critical Adsorption in Spherical Geometry

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    In the framework of mean-field theory the equation for the order-parameter profile in a spherically-symmetric geometry at the bulk critical point reduces to an Emden-Fowler problem. We obtain analytic solutions for the surface universality class of extraordinary transitions in d=4d=4 for a spherical shell, which may serve as a starting point for a pertubative calculation. It is demonstrated that the solution correctly reproduces the Fisher-de Gennes effect in the limit of the parallel-plate geometry.Comment: (to be published in Z. Phys. B), 7 pages, 1 figure, uuencoded postscript file, 8-9
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