Tesis Doctorado

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Browsing Tesis Doctorado by Author "Anabalón Dupuy, Andrés Fernando"

Now showing 1 - 3 of 3
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    Consequences of Torsion in Four Dimensions.
    (Universidad de Concepción, 2024) Medina Medina, Perla Soledad; Anabalón Dupuy, Andrés Fernando
    This thesis addresses two fundamental topics in the field of gravity. First, a reformulation of the Mimetic theory of gravity in first-order formalism for differential forms, i.e., the mimetic version of Einstein-Cartan-Kibble-Sciama (ECKS) gravity. Here we consider different possibilities on how torsion is af- fected by conformal transformations and discuss how this translates into the interpolation between two different conformal transformations of the spin con- nection, parameterized with a zero-form parameter λ. We prove that regardless of the type of transformation one chooses, in this setting torsion remains as a non-propagating field. We also discuss the conservation of the mimetic stress- energy tensor and show that the trace of the total stress-energy tensor is not null but depends on both, the value of λ and spacetime torsion. Second, the Einstein-Hilbert action is studied in the first-order formalism, considering the coupling of a scalar field to different topological invariants. The implications of this coupling on the dynamics of the gravitational field and the evolution of the early universe are analyzed. The results obtained contribute to a better understanding of gravity and its relationship with the topology of spacetime. Second, the Einstein-Hilbert action is studied in the first-order formalism, con- sidering the coupling of a scalar field to different topological invariants. The implications of these couplings on the field equations are analyzed. The re- sults obtained shed light on a theoretical framework where it could be easier to introduce couplings of scalar fields to the geometry.
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    Raices Topológicas de la Gravedad en cuatro dimensiones.
    (Universidad de Concepción, 2007) Anabalón Dupuy, Andrés Fernando; Zanelli, Jorge
    La posibilidad de definir Lagrangeanos gravitacionales usando formas de gauged Wess-Zumino-Witten es explorada. Primeramente se discuten ejemplos mecánicos simples que permiten familiarizarse con los Lagrangeanos tipo Wess-Zumino-Witten. Se hace manifiesta la conexión de estas estructuras con Lagrangeanos gravitacionales en más dimensiones, así como con la teoría de Einstein en cuatro dimensiones. Las ecuaciones de movimiento, de la teoría basada en la forma de gauged Wess-Zumino-Witten en cuatro dimensiones son escritas, y estudiadas, por primera vez. Relaciones off-shell entre ellas son encontradas y usadas para simplificar y discutir la teoría.
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    The thermodynamic role of solitons in the phase space of (super)gravity.
    (Universidad de Concepción, 2024) Quijada Barrera, Constanza del Pilar; Oliva Zapata, Julio Eduardo; Anabalón Dupuy, Andrés Fernando
    In this thesis we study the phase transitions between the planar charged black hole and the charged AdS soliton, which are solutions to the Einstein-AdS theory coupled to linear and non-linear electrodynamics theory. The analysis is carried out in the grand canonical ensemble. The charged planar soliton is obtained as a double analytic continuation of the charged black hole metric, which also involves analytically continuing the electric charge, therefore it appears a magnetic charge on the soliton solution which is associated with a magnetic flux along the non-cyclic planar coordinate. In the case of Einstein-Maxwell theory with negative cosmological constant, we show that there are phase transitions between both solutions depending on the values of electric potential, magnetic flux and temperature. On the other hand, when it is considered the gravitational theory coupled to a non-linear electrodynamics, we show that the phase space of the theory is very rich, containing reen trant phase transitions, as well as triple points, for small values of the coupling controlling the non-linearity of the electrodynamics Lagrangian.
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