2,829 research outputs found

    Non-Abelian (Hyperscaling Violating) Lifshitz Black Holes in General Dimensions

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    We consider Einstein gravities coupled to a cosmological constant and multiple SU(2)SU(2) Yang-Mills fields in general dimensions and find that the theories admit colored Lifshitz solutions with dynamic exponents z>1z>1. We also introduce a Maxwell field and construct exact electric charged black holes that asymptote to the z=Dβˆ’1z=D-1 colored Lifshitz spacetimes and analyse their thermodynamical first law. Furthermore, we introduce a dilaton to the system and construct Lifshitz spacetimes with hyperscaling violations. After turning on the Maxwell field, we obtain a class of hyperscaling violating Lifshitz black holes when ΞΈ=2Dβˆ’2[zβˆ’(Dβˆ’1)]\theta=\frac{2}{D-2}[z-(D-1)].Comment: Latex, 12 pages, a published version in PL

    An Integrated Method Based on PSO and EDA for the Max-Cut Problem

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    The max-cut problem is NP-hard combinatorial optimization problem with many real world applications. In this paper, we propose an integrated method based on particle swarm optimization and estimation of distribution algorithm (PSO-EDA) for solving the max-cut problem. The integrated algorithm overcomes the shortcomings of particle swarm optimization and estimation of distribution algorithm. To enhance the performance of the PSO-EDA, a fast local search procedure is applied. In addition, a path relinking procedure is developed to intensify the search. To evaluate the performance of PSO-EDA, extensive experiments were carried out on two sets of benchmark instances with 800 to 20000 vertices from the literature. Computational results and comparisons show that PSO-EDA significantly outperforms the existing PSO-based and EDA-based algorithms for the max-cut problem. Compared with other best performing algorithms, PSO-EDA is able to find very competitive results in terms of solution quality

    Godel Metrics with Chronology Protection in Horndeski Gravities

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    G\"odel universe, one of the most interesting exact solutions predicted by General Relativity, describes a homogeneous rotating universe containing naked closed time-like curves (CTCs). It was shown that such CTCs are the consequence of the null energy condition in General Relativity. In this paper, we show that the G\"odel-type metrics with chronology protection can emerge in Einstein-Horndeski gravity. We construct such exact solutions also in Einstein-Horndeski-Maxwell and Einstein-Horndeski-Proca theories.Comment: Latex, 11 pages, references adde
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