Examinando por Autor "Zanelli, Jorge"
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Ítem Black hole solutions in Chern-Simons AdS supergravity(Springer Verlag, 2014-08) Giribet, Gaston; Merino, Nelson; Miskovic, Olivera; Zanelli, JorgeWe study charged AdS black hole solutions in five-dimensional Chern-Simons supergravity. The minimal supergroup containing such AdS5 × U(1) configurations is the superunitary group SU(2, 2|N ). For this model, we find analytic black hole solutions that asymptote to locally AdS5 spacetime at the boundary. A solution can carry U(1) charge provided the spacetime torsion is non-vanishing. Thus, we analyze the most general config uration consistent with the local AdS5 isometries in Riemann-Cartan space. The coupling of torsion in the action resembles that of the universal axion of string theory, and it is ulti mately due to this field that the theory acquires propagating degrees of freedom. Through a careful analysis of the canonical structure the local degrees of freedom of the theory are identified in the static symmetric sector of phase space.Ítem Supersymmetric 3D model for gravity with SU(2) gauge symmetry, mass generation and effective cosmological constant(Institute of Physics Publishing, 2015-09) Alvarez, Pedro D.; Pais, Pablo; Rodríguez, Eduardo; Salgado-Rebolledo, Patricio; Zanelli, JorgeA Chern-Simons system in 2+1 dimensions invariant under local Lorentz rotations, SU(2) gauge transformations, and local supersymmetry (SUSY) transformations is proposed. The field content is that of (2+1)-gravity plus an SU(2) gauge field, a spin-1/2 fermion charged with respect to SU(2) and a trivial free abelian gauge field. A peculiarity of the model is the absence of gravitini, although it includes gravity and SUSY. Likewise, no gauginos are present. All the parameters involved in the system are either protected by gauge invariance or emerge as integration constants. An effective mass and effective cosmological constant emerge by spontaneous breaking of local scaling invariance. The vacuum sector is defined by configurations with locally flat Lorentz and SU(2) connections sporting nontrivial global charges. Three-dimensional Lorentz-flat geometries are spacetimes of locally constant negative - or zero - Riemann curvature, which include Minkowski space, AdS3, BTZ black holes, and point particles. These solutions admit different numbers of globally defined, covariantly constant spinors and are therefore good candidates for stable ground states. The fermionic sector in this system could describe the dynamics of electrons in graphene in the long wavelength limit near the Dirac points, with the spin degree of freedom of the electrons represented by the SU(2) label. If this is the case, the SU(2) gauge field would produce a spin-spin interaction giving rise to strong correlation of electron pairs. © 2015 IOP Publishing Ltd.Ítem Supersymmetry of gravitational ground states(Institute of Physics Publishing, 2002-05) Aros, Rodrigo; Martínez, Cristian; Troncoso, Ricardo; Zanelli, JorgeA class of black objects which are solutions of pure gravity with negative cosmological constant are classified through the mapping between the Killing spinors of the ground state and those of the transverse section. It is shown that these geometries must have transverse sections of constant curvature for spacetime dimensions d below seven. For d ≥ 7, the transverse sections can also be euclidean Einstein manifolds. In even dimensions, spacetimes with transverse section of non-constant curvature exist only in d = 8 and 10. This classification goes beyond standard supergravity and the eleven-dimensional case is analyzed. It is shown that if the transverse section has negative scalar curvature, only extended objects can have a supersymmetric ground state. In that case, some solutions are explicitly found whose ground state resembles a wormholeÍtem The BTZ black hole as a Lorentz-flat geometry(Elsevier, 2014) Alvarez, Pedro D.; Pais, Pablo; Rodríguez, Eduardo; Salgado-Rebolledo, Patricio; Zanelli, JorgeIt is shown that 2+1 dimensional anti-de Sitter spacetimes are Lorentz-flat. This means, in particular, that any simply-connected patch of the BTZ black hole solution can be endowed with a Lorentz connection that is locally pure gauge. The result can be naturally extended to a wider class of black hole geometries and point particles in three-dimensional spacetime. © 2014 The Authors.