13,363 research outputs found

    N=1 Supersymmetric Yang-Mills on the lattice at strong coupling

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    We study N=1 supersymmetric SU(N) Yang-Mills theory on the lattice at strong coupling. Our method is based on the hopping parameter expansion in terms of random walks, resummed for any value of the Wilson parameter r in the small hopping parameter region. Results are given for the mesonic (2-gluino) and fermionic (3-gluino) propagators and spectrum.Comment: Latex file. 43 pages. Minor additional comments, references added, typos corrected. Accepted for publication in Int. J. Mod. Phys.

    The isovector dipole strength in nuclei with extreme neutron excess

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    The E1 strength is systematically analyzed in very neutron-rich Sn nuclei, beyond 132^{132}Sn until 166^{166}Sn, within the Relativistic Quasiparticle Random Phase Approximation. The great neutron excess favors the appearance of a deformed ground state for 142162^{142-162}Sn. The evolution of the low-lying strength in deformed nuclei is determined by the interplay of two factors, isospin asymmetry and deformation: while greater neutron excess increases the total low-lying strength, deformation hinders and spreads it. Very neutron rich deformed nuclei may not be as good candidates as stable spherical nuclei like 132^{132}Sn for the experimental study of low-lying E1 strength

    The high-excitation planetary nebulae: NGC 3918 and IC 2448

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    International Ultraviolet Exploration observations of NGC 3918 and IC 2448 are presented. Combining these observations with data in the optical range and computed model structure, the chemical composition for these objects is derived. For NGC 3918 log C = -3.02, log N = -3.61 and log 0 = -3.22; while for IC 2448 log C = -3.44, log N = -81 and log 0 = 3.54

    Determination of the ΔS=1\Delta S = 1 weak Hamiltonian in the SU(4) chiral limit through topological zero-mode wave functions

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    A new method to determine the low-energy couplings of the ΔS=1\Delta S=1 weak Hamiltonian is presented. It relies on a matching of the topological poles in 1/m21/m^2 of three-point correlators of two pseudoscalar densities and a four-fermion operator, measured in lattice QCD, to the same observables computed in the ϵ\epsilon-regime of chiral perturbation theory. We test this method in a theory with a light charm quark, i.e. with an SU(4) flavour symmetry. Quenched numerical measurements are performed in a 2 fm box, and chiral perturbation theory predictions are worked out up to next-to-leading order. The matching of the two sides allows to determine the weak low-energy couplings in the SU(4) limit. We compare the results with a previous determination, based on three-point correlators containing two left-handed currents, and discuss the merits and drawbacks of the two procedures.Comment: 38 pages, 9 figure

    Weak low-energy couplings from topological zero-mode wavefunctions

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    We discuss a new method to determine the low-energy couplings of the ΔS=1\Delta S=1 weak Hamiltonian in the ϵ\epsilon-regime. It relies on a matching of the topological poles in 1/m21/m^2 of three-point functions of two pseudoscalar densities and a four-fermion operator computed in lattice QCD, to the same observables in the Chiral Effective Theory. We present the results of a NLO computation in chiral perturbation theory of these correlation functions together with some preliminary numerical results.Comment: 7 pages. Contribution to Lattice 200

    Onset Event Decoding Exploiting the Rhythmic Structure of Polyphonic Music

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    (c)2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. Published version: IEEE Journal of Selected Topics in Signal Processing 5(6): 1228-1239, Oct 2011. DOI:10.1109/JSTSP.2011.214622

    Generalised verification of the observer property in discrete event systems

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    The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system

    Generalised verification of the observer property in discrete event systems

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    The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system
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