1,579 research outputs found

    Some Comments on Multigrid Methods for Computing Propagators

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    I make three conceptual points regarding multigrid methods for computing propagators in lattice gauge theory: 1) The class of operators handled by the algorithm must be stable under coarsening. 2) Problems related by symmetry should have solution methods related by symmetry. 3) It is crucial to distinguish the vector space VV from its dual space V∗V^*. All the existing algorithms violate one or more of these principles.Comment: 16 pages, LaTeX plus subeqnarray.sty (included at end), NYU-TH-93/07/0

    An algorithm for constructing and classifying the space of small integer weighing matrices

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    In this paper we describe an algorithm for generating all the possible PIW(m,n,k)PIW(m,n,k) - integer m×nm\times n Weighing matrices of weight kk up to Hadamard equivalence. Our method is efficient on a personal computer for small size matrices, up to m≤n=12m\le n=12, and k≤50k\le 50. As a by product we also improved the \textit{\textbf{nsoks}} \cite{riel2006nsoks} algorithm to find all possible representations of an integer kk as a sum of nn integer squares. We have implemented our algorithm in \texttt{Sagemath} and as an example we provide a complete classification for \ n=m=7n=m=7 and k=25k=25. Our list of IW(7,25)IW(7,25) can serve as a step towards finding the open classical weighing matrix W(35,25)W(35,25)

    A Cluster Algorithm for the Z2Z_2 Kalb-Ramond Model

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    A cluster algorithm is presented for the Z2Z_2 Kalb-Ramond plaquette model in four dimensions which dramatically reduces critical slowing. The critical exponent zz is reduced from z>2 z>2 (standard Metropolis algorithm) to z=0.32±0.06z= 0.32\pm0.06. The Cluster algorithm updates the monopole configuration known to be responsible for the second order phase transition.Comment: 9 pages, LaTeX + 7 figures in self-extracting shell archiv
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