Thesis (Ph.D.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2009/06/08). Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 113-119).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 80-82).

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisors: Vadim Kaplunovsky and Willy Fischler. Vita. Includes bibliographical references.

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Orientador: Vicente Pleitez / Mestre

Made available in DSpace on 2018-08-01T21:59:53Z (GMT). No. of bitstreams: 1 tese_3721_.pdf: 950430 bytes, checksum: b54b4523d9d6f764155cd7c49e3599e5 (MD5) Previous issue date: 2009-06-30 / Neste trabalho estudamos o modelo de Jackiw-Teitelboim (modelo JT), como um modelo que tem a estrutura de uma teoria topológica do tipo BF. Em duas dimensões de espaço-tempo, a gravitação pode ser vista como uma teoria de gauge caracterizada pelo grupo de Poincaré ISO(1, 1). Como este grupo não admite uma forma quadrática invariante e não degenerada, o modelo JT trabalha com o grupo (Anti)-de Sitter (A)dS, o grupo SO(2, 1), que contém o grupo de Lorentz como subgrupo e corresponde a uma teoria de gravitação com constante cosmológica. Vemos então, que o grupo (A)dS, tomado como um grupo de gauge, contém naturalmente a simetria de difeomorsmo. Nesta linha investigamos a formulação canônica do modelo JT am de quantizá-lo via o formalismo da gravidade quântica de laços (LQG). Seguindo o programa de quantização canônica de Dirac aplicado ao formalismo de laços, obtemos um espaço de conguração quântico a partir da compaticação de Bohr da linha real, construímos o respectivo espaço de Hilbert cinemático e denimos de forma consistente o operador de volume. Finalmente, tratamos da dinâmica do modelo a nível quântico via a implementação dos vínculos oriundos da teoria clássica do modelo JT no gauge temporal em um espaço de Hilbert adequado.

Gauge/gravity duality is an important tool for learning about strongly coupled gauge theories. This thesis explores a set of examples of this duality in which the field theories have SU(2|4) supersymmetry and discrete sets of vacuum solutions. Specifically, we use the duality to propose Lagrangian definitions of type IIA Little String Theory on S⁵ as double-scaling limits of the Plane-Wave Matrix Model, maximally supersymmetric Yang-Mills theory on R x S² and N=4 supersymmetric Yang-Mills theory on R×S³/Zk. We find the supergravity solutions dual to generic vacua of the Plane-Wave Matrix Model and maximally supersymmetric Yang-Mills theory on R×S². We use the supergravity duals to calculate new instanton amplitudes for the Plane-Wave Matrix Model at strong coupling. Finally, we study a natural coarse-graining of the vacua, and find that the associated geometries are singular. We define an entropy functional that vanishes for regular geometries, is non-zero for singular geometries, and is maximized by the thermal state. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Gauge theories which have a phase transition could be useful in the study of quark confinement. One of the simplest theories containing a phase transition is the Coleman-Weinberg model of massless scalar electrodynamics. The calculation of the renormalized effective potential for the Coleman-Weinberg model is reviewed in detail using the path integral formalism. The effective potential is evaluated at the one-loop level to show that the model exhibits dynamical symmetry breaking at zero temperature. The divergent parts are shown to be renormalizable to two-loop order. The temperature dependence of the effective potential is then calculated to one-loop in order to demonstrate that the symmetry of the model is restored at high temperature, indicating a phase transition. Finally, for models which exhibit this type of behaviour, applications to SU(n) theories of quarks are discussed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate