420 research outputs found

    Classical String Solutions in Effective Infrared Theory of SU(3) Gluodynamics

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    We investigate string solutions to the classical equations of motion ("classical QCD strings") for a dual Ginzburg-Landau model corresponding to SU(3) gluodynamics in an abelian projection. For a certain relation between couplings of the model the string solutions are defined by first order differential equations. These solutions are related to vortex configurations of the Abelian Higgs model in the Bogomol'ny limit. An analytic expression for the string tension is derived and the string-string interactions are discussed. Our results imply that the vacuum of SU(3) gluodynamics is near a border between type-I and type-II dual superconductivity.Comment: 7 pages, LaTeX2e; v2: references added and typos correcte

    Heavy monopole potential in gluodynamics

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    We discuss predictions for the interaction energy of the fundamental monopoles in gluodynamics introduced via the 't Hooft loop. At short distances, the heavy monopole potential is calculable from first principles. At larger distances, we apply the Abelian dominance models. We discuss the measurements which would be crucial to distinguish between various models. Non-zero temperatures are also considered. Our predictions are in qualitative agreement with the existing lattice data. We discuss further measurements which would be crucial to check the model.Comment: 3 pages, 1 figure, Lattice2001(confinement

    Short Strings and Gluon Propagator in the Infrared Region

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    We discuss how infrared region influence on short distance physics via new object, called ``short string''. This object exists in confining theories and violates the operator product expansion. Most analytical results are obtained for the dual Abelian Higgs theory, while phenomenological arguments are given for QCD.Comment: LATTICE99(confine) - 6 page

    Gluodynamics in external field in dual superconductor approach

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    We show that gluodynamics in an external Abelian electromagnetic field should possess a deconfining phase transition at zero temperature. Our analytical estimation of the critical external field is based on the dual superconductor picture which is formulated in the Euclidean space suitable for lattice calculations. A dual superconductor model corresponding to the SU(2) gluodynamics possesses confinement and deconfinement phases below and, respectively, above the critical field. A dual superconductor model for the SU(3) gauge theory predicts a rich phase structure containing confinement, asymmetric confinement and deconfinement phases. The quark bound states in these phases are analyzed. Inside the baryon the strings are Y--shaped as predicted by the dual superconductor picture. This shape is geometrically asymmetric in the asymmetric confinement phases. The results of the paper can be used to check the dual superconductor mechanism in gluodynamics.Comment: 11 pages, 2 figures, LaTeX2e; v2: minor corrections, to be published in Phys.Lett.

    Assessing adherence to Antihypertensive therapy in primary health care in Namibia: findings and implications

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    Namibia has the highest burden and incidence of hypertension in sub-Sahara Africa. Though non-adherence to antihypertensive therapy is an important cardiovascular risk factor, little is known about potential ways to improve adherence in Namibia following universal access. The objective of this study is to validate the Hill-Bone compliance scale and determine the level and predictors of adherence to antihypertensive treatment in primary health care settings in sub-urban townships of Windhoek, Namibia

    Towards Abelian-like formulation of the dual gluodynamics

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    We consider gluodynamics in case when both color and magnetic charges are present. We discuss first short distance physics, where only the fundamental |Q|=1 monopoles introduced via the `t Hooft loop can be considered consistently. We show that at short distances the external monopoles interact as pure Abelian objects. This result can be reproduced by a Zwanziger-type Lagrangian with an Abelian dual gluon. We introduce also an effective dual gluodynamics which might be a valid approximation at distances where the monopoles |Q|=2 can be considered as point-like as well. Assuming the monopole condensation we arrive at a model which is reminiscent in some respect of the Abelian Higgs model but, unlike the latter leaves space for the Casimir scaling.Comment: 28+1 pp., Latex2e, 1 figur

    Tricritical Behavior of Two-Dimensional Scalar Field Theories

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    We compute by Monte Carlo numerical simulations the critical exponents of two-dimensional scalar field theories at the λϕ6\lambda\phi^6 tricritical point. The results are in agreement with the Zamolodchikov conjecture based on conformal invariance.Comment: 13 pages, uuencode tar-compressed Postscript file, preprint numbers: IF/UFRJ/25/94, DFTUZ 94.06 and NYU--TH--94/10/0

    Weak convergence of finite element approximations of linear stochastic evolution equations with additive noise II. Fully discrete schemes

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    We present an abstract framework for analyzing the weak error of fully discrete approximation schemes for linear evolution equations driven by additive Gaussian noise. First, an abstract representation formula is derived for sufficiently smooth test functions. The formula is then applied to the wave equation, where the spatial approximation is done via the standard continuous finite element method and the time discretization via an I-stable rational approximation to the exponential function. It is found that the rate of weak convergence is twice that of strong convergence. Furthermore, in contrast to the parabolic case, higher order schemes in time, such as the Crank-Nicolson scheme, are worthwhile to use if the solution is not very regular. Finally we apply the theory to parabolic equations and detail a weak error estimate for the linearized Cahn-Hilliard-Cook equation as well as comment on the stochastic heat equation

    An integral method for solving nonlinear eigenvalue problems

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    We propose a numerical method for computing all eigenvalues (and the corresponding eigenvectors) of a nonlinear holomorphic eigenvalue problem that lie within a given contour in the complex plane. The method uses complex integrals of the resolvent operator, applied to at least kk column vectors, where kk is the number of eigenvalues inside the contour. The theorem of Keldysh is employed to show that the original nonlinear eigenvalue problem reduces to a linear eigenvalue problem of dimension kk. No initial approximations of eigenvalues and eigenvectors are needed. The method is particularly suitable for moderately large eigenvalue problems where kk is much smaller than the matrix dimension. We also give an extension of the method to the case where kk is larger than the matrix dimension. The quadrature errors caused by the trapezoid sum are discussed for the case of analytic closed contours. Using well known techniques it is shown that the error decays exponentially with an exponent given by the product of the number of quadrature points and the minimal distance of the eigenvalues to the contour
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