396 research outputs found

    A reciprocity formula from abelian BF and Turaev-Viro theories

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    In this article we show that the use of Deligne-Beilinson cohomology in the context of the U(1)U(1) BF theory on a closed 3-manifold MM yields a discrete ZN\Z_N BF theory whose partition function is an abelian TV invariant of MM. By comparing the expectation values of the U(1)U(1) and ZN\mathbb{Z}_N holonomies in both BF theories we obtain a reciprocity formula

    Deligne-Beilinson cohomology and abelian link invariants: torsion case

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    For the abelian Chern-Simons field theory, we consider the quantum functional integration over the Deligne-Beilinson cohomology classes and present an explicit path-integral non-perturbative computation of the Chern-Simons link invariants in SO(3)RP3SO(3)\simeq\mathbb{R}P^3, a toy example of 3-manifold with torsion

    Higher dimensional abelian Chern-Simons theories and their link invariants

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    The role played by Deligne-Beilinson cohomology in establishing the relation between Chern-Simons theory and link invariants in dimensions higher than three is investigated. Deligne-Beilinson cohomology classes provide a natural abelian Chern-Simons action, non trivial only in dimensions 4l+34l+3, whose parameter kk is quantized. The generalized Wilson (2l+1)(2l+1)-loops are observables of the theory and their charges are quantized. The Chern-Simons action is then used to compute invariants for links of (2l+1)(2l+1)-loops, first on closed (4l+3)(4l+3)-manifolds through a novel geometric computation, then on R4l+3\mathbb{R}^{4l+3} through an unconventional field theoretic computation.Comment: 40 page

    Abelian BF theory and Turaev-Viro invariant

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    The U(1) BF Quantum Field Theory is revisited in the light of Deligne-Beilinson Cohomology. We show how the U(1) Chern-Simons partition function is related to the BF one and how the latter on its turn coincides with an abelian Turaev-Viro invariant. Significant differences compared to the non-abelian case are highlighted.Comment: 47 pages and 6 figure

    Deligne-Beilinson Cohomology and Abelian Link Invariants

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    For the Abelian Chern-Simons field theory, we consider the quantum functional integration over the Deligne-Beilinson cohomology classes and we derive the main properties of the observables in a generic closed orientable 3-manifold. We present an explicit path-integral non-perturbative computation of the Chern-Simons link invariants in the case of the torsion-free 3-manifolds S³, S¹ × S² and S¹ × Σg

    Material parameters identification: Gradient-based, genetic and hybrid optimization algorithms

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    This paper presents two procedures for the identification of material parameters, a genetic algorithm and a gradient-based algorithm. These algorithms enable both the yield criterion and the work hardening parameters to be identified. A hybrid algorithm is also used, which is a combination of the former two, in such a way that the result of the genetic algorithm is considered as the initial values for the gradient-based algorithm. The objective of this approach is to improve the performance of the gradient-based algorithm, which is strongly dependent on the initial set of results. The constitutive model used to compare the three different optimization schemes uses the Barlat'91 yield criterion, an isotropic Voce type law and a kinematic Lemaitre and Chaboche law, which is suitable for the case of aluminium alloys. In order to analyse the effectiveness of this optimization procedure, numerical and experimental results for an EN AW-5754 aluminium alloy are compared.http://www.sciencedirect.com/science/article/B6TWM-4SJGWMW-1/1/01e8be60ce61e8fc30473d85439fbe3

    On P_4-tidy graphs

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    We study the P_4-tidy graphs, a new class defined by Rusu [30] in order to illustrate the notion of P_4-domination in perfect graphs. This class strictly contains the P_4-extendible graphs and the P_4-lite graphs defined by Jamison & Olariu in [19] and [23] and we show that the P_4-tidy graphs and P_4-lite graphs are closely related. Note that the class of P_4-lite graphs is a class of brittle graphs strictly containing the P_4-sparse graphs defined by Hoang in [14]. McConnel & Spinrad [2] and independently Cournier & Habib [5] have shown that the modular decomposition tree of any graph is computable in linear time. For recognizing in linear time P_4-tidy graphs, we apply a method introduced by Giakoumakis in [9] and Giakoumakis & Fouquet in [6] using modular decomposition of graphs and we propose linear algorithms for optimization problems on such graphs, as clique number, stability number, chromatic number and scattering number. We show that the Hamiltonian Path Problem is linear for this class of graphs. Our study unifies and generalizes previous results of Jamison & Olariu ([18], [21], [22]), Hochstattler & Schindler[16], Jung [25] and Hochstattler & Tinhofer [15]

    Experimental study of a proximity focusing Cherenkov counter prototype for the AMS experiment

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    A study prototype of Proximity Focussing Ring Imaging Cherenkov counter has been built and tested with several radiators using separately cosmic-ray particles and 12C beam fragmentation products at several energies. Counter prototype and experimental setup are described, and the results of measurements reported and compared with simulation results.The performances are discussed in the perspective of the final counter design.Comment: 27 pages, 16 figures, submitted to NIM
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