Browsing by Author "Miskovic, Olivera"

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    Dynamics and BPS states of AdS5 supergravity with a Gauss-Bonnet term
    (2006) Miskovic, Olivera; Troncoso, Ricardo; Zanelli, Jorge
    Some dynamical aspects of five-dimensional supergravity as a Chem-Simons theory for the SU(2,2 vertical bar N) group, are analyzed. The gravitational sector is described by the Einstein-Hilbert action with negative cosmological constant and a Gauss-Bonnet term with a fixed coupling. The interaction between matter and gravity is characterized by intricate couplings which give rise to dynamical features not present in standard theories. Depending on the location in phase space, the dynamics can possess different number of propagating degrees of freedom, including purely topological sectors. This inhomogeneity of phase space requires special care in the analysis.
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    Fluctuations around classical solutions for gauge theories in Lagrangian and Hamiltonian approach
    (2006) Miskovic, Olivera; Pons, Josep M.
    We analyse the dynamics of gauge theories and constrained systems in general under small perturbations around a classical solution in both Lagrangian and Hamiltonian formalisms. We prove that a fluctuations theory, described by a quadratic Lagrangian, has the same constraint structure and number of physical degrees of freedom as the original non-perturbed theory, assuming the non-degenerate solution has been chosen. We show that the number of Noether gauge symmetries is the same in both theories, but that the gauge algebra in the fluctuations theory becomes Abelianized. We also show that the fluctuations theory inherits all functionally independent rigid symmetries from the original theory and that these symmetries are generated by linear or quadratic generators according to whether the original symmetry is preserved by the background or is broken by it. We illustrate these results with examples.
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    On boundary conditions in three-dimensional AdS gravity
    (2006) Miskovic, Olivera; Olea, Rodrigo
    A finite action principle for three-dimensional gravity with negative cosmological constant, based on a boundary condition for the asymptotic extrinsic curvature, is considered. The bulk action appears naturally supplemented by a boundary term that is one half the Gibbons-Hawking term, that makes the Euclidean action and the Noether charges finite without additional Dirichlet counterterms. The consistency of this boundary condition with the Dirichlet problem in AdS gravity and the Chern-Simons formulation in three dimensions, and its suitability for the higher odd-dimensional case, are also discussed. (c) 2006 Elsevier B.V. All rights reserved.