15 research outputs found

    The SU(2) Skyrme model and anomaly

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    The SU(2) Skyrme model,expanding in the collective coordinates variables, gives rise to second-class constraints. Recently this system was embedded in a more general Abelian gauge theory using the BFFT Hamiltonian method. In this work we quantize this gauge theory computing the Noether current anomaly using for this two different methods: an operatorial Dirac first class formalism and the non-local BV quantization coupled with the Fujikawa regularization procedure.Comment: 6 pages, Revtex. Final version to be published in Physics Letters

    Minimal conditions for the creation of a Friedman-Robertson-Walker universe from a "bounce"

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    We investigate the minimal conditions under which the creation of our universe might arise due to a "bounce" from a previous collapse, rather than an explosion from a big-bang singularity. Such a bounce is sometimes referred to as a Tolman wormhole. We subject the bounce to a general model-independent analysis along the lines of that applied to the Morris-Thorne traversable wormholes, and show that there is always an open temporal region surrounding the bounce over which the strong energy condition (SEC) must be violated. On the other hand, all the other energy conditions can easily be satisfied. In particular, we exhibit an inflation-inspired model in which a big bounce is "natural".Comment: 4 pages, ReV-TeX 3.

    Effective potential for the massless KPZ equation

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    In previous work we have developed a general method for casting a classical field theory subject to Gaussian noise (that is, a stochastic partial differential equation--SPDE) into a functional integral formalism that exhibits many of the properties more commonly associated with quantum field theories (QFTs). In particular, we demonstrated how to derive the one-loop effective potential. In this paper we apply the formalism to a specific field theory of considerable interest, the massless KPZ equation (massless noisy vorticity-free Burgers equation), and analyze its behaviour in the ultraviolet (short-distance) regime. When this field theory is subject to white noise we can calculate the one-loop effective potential and show that it is one-loop ultraviolet renormalizable in 1, 2, and 3 space dimensions, and fails to be ultraviolet renormalizable in higher dimensions. We show that the one-loop effective potential for the massless KPZ equation is closely related to that for lambda phi^4 QFT. In particular we prove that the massless KPZ equation exhibits one-loop dynamical symmetry breaking (via an analog of the Coleman-Weinberg mechanism) in 1 and 2 space dimensions, and that this behaviour does not persist in 3 space dimensions.Comment: 13 pages, LaTeX 209, ReV_TeX 3.2, three *.eps figures, epsf.st

    Sonoluminescence: Two-photon correlations as a test of thermality

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    In this Letter we propose a fundamental test for probing the thermal nature of the spectrum emitted by sonoluminescence. We show that two-photon correlations can in principle discriminate between real thermal light and the quasi-thermal squeezed-state photons typical of models based on the dynamic Casimir effect. Two-photon correlations provide a powerful experimental test for various classes of sonoluminescence models.Comment: 6 pages, revtex 3; revised to include more discussion of finite volume effects; physics conclusions unchanged; to appear in Physics Letters

    The direct boundary element method: 2D site effects assessment on laterally varying layered media (methodology)

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    The Direct Boundary Element Method (DBEM) is presented to solve the elastodynamic field equations in 2D, and a complete comprehensive implementation is given. The DBEM is a useful approach to obtain reliable numerical estimates of site effects on seismic ground motion due to irregular geological configurations, both of layering and topography. The method is based on the discretization of the classical Somigliana's elastodynamic representation equation which stems from the reciprocity theorem. This equation is given in terms of the Green's function which is the full-space harmonic steady-state fundamental solution. The formulation permits the treatment of viscoelastic media, therefore site models with intrinsic attenuation can be examined. By means of this approach, the calculation of 2D scattering of seismic waves, due to the incidence of P and SV waves on irregular topographical profiles is performed. Sites such as, canyons, mountains and valleys in irregular multilayered media are computed to test the technique. The obtained transfer functions show excellent agreement with already published results

    Steady-state moisture diffusion in curved walls, in the absence of condensate flow, via the BEM: a practical Civil Engineering approach (Glaser method)

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    The influence of the curvature radius of curved walls on the condensation patterns across a single panel homogeneous wall is analysed under steady-state conditions. Condensation is defined according to the Glaser approach, which is a practical tool in building design, recommended by the DIN 4108 and prEN ISO 13788 standards. This methodology uses an iterative process, which requires the resolution of temperature equilibrium and several vapour pressure equilibrium problems. Each of these potential problems is solved using the Boundary Element Method (BEM). The iterative process is first implemented and validated by applying it to the definition of condensation patterns across a hollow cylinder, for which the solution is calculated analytically. The BEM is then applied to the curved wall models, identifying the zones where condensation occurs and quantifying the amount of liquid water generated.http://www.sciencedirect.com/science/article/B6V23-47WD40H-2/1/85b0c63e211f2b4fd00ad0dd901ca69

    Weak formulation of axi-symmetric frictionless contact problems with boundary elements: Application to interface cracks

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    A boundary element formulation of the axi-symmetric elastic problem, including contact conditions for multi-domain problems, is presented in this paper and applied to the analysis of interface cracks. A weak formulation of the equilibrium and compatibility equations has been developed to allow non-conforming discretizations to be used in the contacting boundaries. In order to obtain a high accuracy in the solution (employing continuous linear elements), the singular terms appearing in the axi-symmetric boundary integral equations have been integrated analytically. The numerical analysis of a penny-shaped crack at the interface of two dissimilar materials and of a fibre-matrix debonding crack in the single fibre fragmentation test is presented. © 2004 Elsevier Ltd. All rights reserved
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