3,022 research outputs found

    The string tension in SU(N) gauge theory from a careful analysis of smearing parameters

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    We report a method to select optimal smearing parameters before production runs and discuss the advantages of this selection for the determination of the string tension.Comment: Contribution to Lat97 poster session, title was 'How to measure the string tension', 3 pages, 5 colour eps figure

    Do classical configurations produce Confinement?

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    We show that certain classical SU(2) pure gauge configurations give rise to a non-zero string tension. We then investigate cooled configurations generated by Monte Carlo simulations on the lattice and find similar properties. We infer evidence in favour of a classical model of Confinement.Comment: Uuencoded, Z-compressed and tarred file of the TeX file submit.tex and PostScript files Stnt.eps and Stst.eps. 11 pages of text and two figure

    Towards an Abelian Formulation of Lattice QCD Confinement

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    We probe for operators occurring in the APQCD(``abelian-projected QCD'') action by evaluating abelian-projected 11-plaquette spectral densities in pure gauge SU(3)SU(3) fixed to maximal abelian gauge. Couplings BAPQCD(q,L)B_{APQCD}(q,L) are extracted from the spectral densities for each representation qq, L×LL\times L plaquette. While APQCD is dominated by a q=L=1q=L=1 resonance, we also find evidence for weakly coupled L=2L=2 plaquettes. Moreover, since BAPQCD(1,1)>BQED(1,1)B_{APQCD}(1,1) > B_{QED}(1,1) even if βQED>βc\beta_{QED} > \beta_c, L>1L>1 plaquettes must be significant since APQCD is confining.Comment: 1+11 pages, fixed minor postscript erro

    Competition between Diffusion and Fragmentation: An Important Evolutionary Process of Nature

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    We investigate systems of nature where the common physical processes diffusion and fragmentation compete. We derive a rate equation for the size distribution of fragments. The equation leads to a third order differential equation which we solve exactly in terms of Bessel functions. The stationary state is a universal Bessel distribution described by one parameter, which fits perfectly experimental data from two very different system of nature, namely, the distribution of ice crystal sizes from the Greenland ice sheet and the length distribution of alpha-helices in proteins.Comment: 4 pages, 3 figures, (minor changes

    Magnetic fields in the early universe in the string approach to MHD

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    There is a reformulation of magnetohydrodynamics in which the fundamental dynamical quantities are the positions and velocities of the lines of magnetic flux in the plasma, which turn out to obey equations of motion very much like ideal strings. We use this approach to study the evolution of a primordial magnetic field generated during the radiation-dominated era in the early Universe. Causality dictates that the field lines form a tangled random network, and the string-like equations of motion, plus the assumption of perfect reconnection, inevitably lead to a self-similar solution for the magnetic field power spectrum. We present the predicted form of the power spectrum, and discuss insights gained from the string approximation, in particular the implications for the existence or not of an inverse cascade.Comment: 12 pages, 2 figure

    BioConcens: Biomass and bioenergy production agriculture – consequences for soil fertility, environment, spread of animal parasites and socio-economy

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    The research programme called “international research cooperation and organic integrity” was commenced for a period 2006-2010. It is coordinated by DARCOF (The Danish Research Centre for Organic Farming). The whole programme, with acronym DARCOF III, consists of 15 projects (http://www.darcof.dk/research/darcofiii/index.html). One of them is BIOCONCENS - Biomass and bioenergy production in organic farming – consequences for soil fertility, environment, spread of animal parasites and socio-economy (http://www.bioconcens.elr.dk/uk/). The production of bioenergy in organic agriculture (OA) can reduce its dependency of fossil fuels and decrease green house gasses emission; consequently it will increase sustainability of organic farms. Biorefinery concept based on co-production of biogas, bioethanol and protein fodder in organic farming will be developed within the BIOCONCENS project and the background for the project and the different work packages will be presented in this paper

    Energy Losses (Gains) of Massive Coloured Particles in Stochastic Colour Medium

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    The propagation of massive coloured particles in stochastic background chromoelectric field is studied using the semiclassical equations of motion. Depending on the nature of the stochastic background we obtain the formulae for the energy losses of heavy coloured projectile in nonperturbative hadronic medium and for the energy gains in the stochastic field present, e.g., in the turbulent plasma. The result appears to be significantly dependent on the form of the correlation function of stochastic external fieldComment: 9 pages, BI-TP 94/15, plain LaTe
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