Examinando por Autor "Aros, Rodrigo"
Mostrando 1 - 12 de 12
Resultados por página
Opciones de ordenación
Ítem A new class of regular black holes in Einstein Gauss-Bonnet gravity with localized sources of matter(Elsevier B.V., 2023-09-10) Estrada, Milko; Aros, RodrigoWe provide a new regular black hole solution (RBH) in Einstein Gauss-Bonnet (EGB) gravity with localized sources of matter in the energy–momentum tensor. We determine the necessary constraints in order for the solution to be regular. Although we use a specific form for the energy density as a test of proof, these constraints could serve as a recipe for constructing several new RBH solutions in EGB gravity with localized sources. Due to that the usual first law of thermodynamics is not valid for RBH, so we rewrite the first law for EGB, which leads to correct values of entropy and volume. The size of the extremal black hole, whose temperature vanishes, becomes smaller for larger dimensions, whose radius could be of the order of the Planck units, thus the evaporation would stop once the horizon radius contracts up to a value close to the Planck length, which could be related with the apparition of quantum effects. Furthermore, the presence of matter fields in the energy–momentum tensor induces two phase transitions, where there are two regions of stability. This differs from the vacuum EGB solution, where the specific heat is always negative without phase transition as occurs in Schwarzschild black hole.Ítem An Alternative Study about the Geometry and the First Law of Thermodynamics for AdS Lovelock Gravity, Using the Definition of Conserved Charges(MDPI, 2022-09) Aros, Rodrigo; Estrada, Milko; Pereira, PabloIn this work, we introduce an extension of the study of the first law of thermodynamics of black holes based on the geometry of the extended phase space for AdS Lovelock gravities, which includes changes in scales. As expected, the result obtained coincides with the previously known four-dimensional case. For higher dimensions, the result is the rise of two new contributions to the first law of thermodynamics. The first term corresponds to corrections of the usual definition of thermodynamic volumes at the horizon due to the presence of the higher curvature terms. The second term arises in odd dimensions, comes from the asymptotic region, and corresponds to a scale transformation of the form (Formula presented.), with l the AdS radius and ℓ a parameter. A particularly interesting case corresponds to the Chern Simons gravity where the change scale does not generate a contribution at the asymptotic region, likely due to the Chern Simons AdS local symmetry.Ítem An Alternative Study about the Geometry and the First Law of Thermodynamics for AdS Lovelock Gravity, Using the Definition of Conserved Charges(MDPI, 2022-09) Aros, Rodrigo; Estrada, Milko; Pereira, PabloIn this work, we introduce an extension of the study of the first law of thermodynamics of black holes based on the geometry of the extended phase space for AdS Lovelock gravities, which includes changes in scales. As expected, the result obtained coincides with the previously known four-dimensional case. For higher dimensions, the result is the rise of two new contributions to the first law of thermodynamics. The first term corresponds to corrections of the usual definition of thermodynamic volumes at the horizon due to the presence of the higher curvature terms. The second term arises in odd dimensions, comes from the asymptotic region, and corresponds to a scale transformation of the form (Formula presented.), with l the AdS radius and ℓ a parameter. A particularly interesting case corresponds to the Chern Simons gravity where the change scale does not generate a contribution at the asymptotic region, likely due to the Chern Simons AdS local symmetry. © 2022 by the authors.Ítem Conformal anomalies of higher spin fields(Universidad Andrés Bello, 2017) Acevedo Espinoza, Sebastián; Aros, Rodrigo; Díaz, Danilo; Facultad de Ciencias ExactasLa anomalía de traza de un campo de Conformal Higher Spin en cuatro dimensiones se calcula de forma holográfi ca. Obtenemos la anomalía de traza Tipo-A y Tipo-B para toda la familia de CHS en 4D. Las bases invariantes de Weyl, donde el término de Euler es tratado por la Q-curvatura parece más adecuado para los cálculos y también permite para una receta holográfi ca simple y útil. Nuestros hallazgos holográfi cos concuerdan con los resultados obtenidos por medio de heat kernel asumiendo la factorización del operador cinético de derivadas altas de CHS en espacios de Einstein. En esta tesis se pretenderá usar la correspondencia AdS=CFT [1] calculando la función partición a one-loop en una métrica Poincaré-Einstein (AdS5) llevándola a un borde Einstein reproduciendo las anomalías Tipo-A y Tipo-B comparándolas con las anomalías que obtuvo A.A. Tseytlin [2] en una CFT en una esfera deformada S4 q , implica que el tensor de Weyl es distinto de cero. En el lado de holográficaa usaremos un campo de Fronsdal en AdS5 con acople de Lichnerowicz a one-loop, con este acople al campo de Fronsdal vamos a calcular las anomalías las Tipo-A y Tipo-B usando las receta holográfi ca [3] en el bulk evaluando en el borde.Ítem Entropy of a Taub-bolt-AdS spacetime from an improved action principle(American Physical Society, 2017-07) Aros, RodrigoIn this article the study of four-dimensional spaces with NUT charges and their ground states is continued. In particular, through the introduction of an improved action principle containing topological densities, it is shown that these spaces have simple and sound thermodynamical relations. As an example, the entropy of the Taub-bolt-AdS solution is computed in terms of a Noether charge. © 2017 American Physical Society.Ítem First-order Lagrangian of Lovelock gravity and applications(Universidad Andrés Bello, 2022) Guilleminot Arellano, Pablo; Olea, Rodrigo; Merino, Nelson; Faraggi, Alberto; Miskovic, Olivera; Aros, Rodrigo; Corral, Cristóbal; Facultad de Ciencias ExactasEn este trabajo, se analizan, analíticamente, aspectos de evolución espacial en gravedad de Lovelock. Se muestra que la adición de términos de Myers a la acción elimina las derivadas de segundo orden respecto a la variable de evolución. Así, la conexión entre el problema de Dirichlet y Lagrangianos de primer orden es establecida. Luego, se exhibe como la transformada de Legendre de este último permite calcular directamente el Hamiltoniano del sistema para la misma variable de evolución. Con estos resultados, se analiza el comportamiento de cáscaras delgadas con masa en el contexto de gravedad de Lovelock. Para esto, se trabaja el principio variacional escrito en un set adaptado de coordenadas válido cerca de la cáscara. Se concluye que la cantidad que es discontínua en la cáscara es el momentum canónico. Finalmente se obtienen algunas expresiones explicitas para configuraciones con simetría esférica.Ítem Magnetic mass in 4D AdS gravity(AMER PHYSICAL SOC, 2016-04) Araneda, René; Aros, Rodrigo; Miskovic, Olivera; Olea, RodrigoWe provide a fully covariant expression for the diffeomorphic charge in four-dimensional anti-de Sitter gravity, when the Gauss-Bonnet and Pontryagin terms are added to the action. The couplings of these topological invariants are such that the Weyl tensor and its dual appear in the on-shell variation of the action and such that the action is stationary for asymptotic (anti-)self-dual solutions in the Weyl tensor. In analogy with Euclidean electromagnetism, whenever the self-duality condition is global, both the action and the total charge are identically vanishing. Therefore, for such configurations, the magnetic mass equals the Ashtekhar-Magnon-Das definition.Ítem Matching one-loop divergences in 7D Einstein and 6D Conformal Gravities(Wiley-VCH Verlag, 2019-11) Aros, Rodrigo; Bugini, Fabrizzio; Díaz, Danilo E.Within the context of AdS/CFT correspondence, we first compute the one-loop infrared (IR) divergences of 7D Einstein gravity in a certain Poincaré-Einstein background metric. Then, we compute the one-loop ultraviolet (UV) divergences of 6D conformal gravity on the conformal boundary. We verify the equality of the above results that stem from the IR–UV connection of the duality dictionary. Key ingredients are heat kernel techniques, factorization of the boundary higher-derivative kinetic operator for the Weyl graviton on the 6D Einstein metric, and Wentzel–Kramers–Brillouin (WKB) exactness of the Einstein graviton in the chosen 7D Poincaré-Einstein background. Overall, we elucidate the way in which the 6D results containing the type-A and type-B conformal anomalies for the Weyl graviton are encoded in the 7D “hologram” given by the fluctuation determinant for the Einstein graviton. We finally discuss possible extensions to include higher-spin fields. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimÍtem Regular black holes and its thermodynamics in Lovelock gravity(Springer New York LLC, 2019-03) Estrada, Milko; Aros, RodrigoIn this work two new families of non-singular or regular black hole solutions are displayed. These black holes behave as de Sitter space near its center and have a well defined AdS asymptotic region for negative cosmological constant. These solutions are constructed on a general ground through the introduction of a finite density of mass/energy. This removes the usual singularity of a black hole and also introduces a new internal geometry. The thermodynamic properties of these solutions are discussed as well. © 2019, The Author(s).Ítem Regular black holes with Λ>0 and its evolution in Lovelock gravity(Springer New York LLC, 2019-09) Estrada, Milko; Aros, RodrigoIn this work it is shown that the thermodynamics of regular black holes with a cosmological horizon, which are solutions of Lovelock gravity, determines that they must evolve either into a state where the black hole and cosmological horizons have reached thermal equilibrium or into an extreme black hole geometry where the black hole and cosmological horizons have merged. This differs from the behavior of Schwarzschild de Sitter geometry which evolves into a de Sitter space, the ground state of the space of solutions. This occurs due to a phase transition of the heat capacity of the black hole horizon. To perform that analysis it is shown that at each horizon a local first law of thermodynamics can be obtained from the gravitational equations. © 2019, The Author(s).Ítem Study of Branes with Variable Tension(Institute of Physics Publishing, 2017-11) Aros, Rodrigo; Estrada, MilkoIn this work we study a brane world model with variable tension, which gives rise to four-dimensional cosmologies. The brane worlds obtained correspond to Eötvös branes whose (internal) geometry can be casted as either a four-dimensional (A)dS4 or a standard radiation period cosmology. The matter dominated period is discussed as well. © 2017 Chinese Physical Society and 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 wormhole