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Construímos uma deformação integrável da ação de espinores puros no espaço AdS5×S5 baseada na teoria de perturbação homológica. Mostramos que o modelo resultante descreve uma corda movendo-se em um superespaço eta. Nesse sentido, estabelecemos um mapa entre operadores de vértices na cohomologia da carga BRST em AdS5×S5 e o superespaço / We construct an integrable deformation of the AdS5×S5 pure spinor action based on homological perturbation theory. We show that the resulting model describes a pure spinor string moving in an eta-target superspace. In that sense, we establish a one-to one map between vertex operators in the cohomology of the undeformed BRST charge and the eta-target space.

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This dissertation begins with a review of Calabi-Yau manifolds and their moduli spaces, flux compactification largely tailored to the case of type IIb supergravity, and Coleman-De Luccia vacuum decay. The three chapters that follow present the results of novel research conducted as a graduate student. Our first project is concerned with bubble collisions in single scalar field theories with multiple vacua. Lorentz boosted solitons traveling in one spatial dimension are used as a proxy to the colliding 3-dimensional spherical bubble walls. Recent work found that at sufficiently high impact velocities collisions between such bubble vacua are governed by "free passage" dynamics in which field interactions can be ignored during the collision, providing a systematic process for populating local minima without quantum nucleation. We focus on the time period that follows the bubble collision and provide evidence that, for certain potentials, interactions can drive significant deviations from the free passage bubble profile, thwarting the production of a new patch with different field value. However, for simple polynomial potentials a fine-tuning of vacuum locations is required to reverse the free passage kick enough that the field in the collision region returns to the original bubble vacuum. Hence we deem classical transitions mediated by free passage robust. Our second project continues with soliton collisions in the limit of relativistic impact velocity, but with the new feature of nontrivial field space curvature. We establish a simple geometrical interpretation of such collisions in terms of a double family of field profiles whose tangent vector fields stand in mutual parallel transport. This provides a generalization of the well-known limit in flat field space (free passage). We investigate the limits of this approximation and illustrate our analytical results with numerical simulations. In our third and final project we investigate the distribution of field theories that arise from the low energy limit of flux vacua built on type IIb string theory compactified on the mirror quintic. For a large collection of these models, we numerically determine the distribution of Taylor coefficients in a polynomial expansion of each model's scalar potential to fourth order. We provide an analytic explanation of the proncounced hierarchies exhibited by the random sample of masses and couplings generated numerically. The analytic argument is based on the structure of masses in no scale supergravity and the divergence of the Yukawa coupling at the conifold point in the moduli space of the mirror quintic. Our results cast the superpotential vev as a random element whose capacity to cloud structure vanishes as the conifold is approached.

Construímos uma deformação integrável da ação de espinores puros no espaço AdS5×S5 baseada na teoria de perturbação homológica. Mostramos que o modelo resultante descreve uma corda movendo-se em um superespaço eta. Nesse sentido, estabelecemos um mapa entre operadores de vértices na cohomologia da carga BRST em AdS5×S5 e o superespaço / We construct an integrable deformation of the AdS5×S5 pure spinor action based on homological perturbation theory. We show that the resulting model describes a pure spinor string moving in an eta-target superspace. In that sense, we establish a one-to one map between vertex operators in the cohomology of the undeformed BRST charge and the eta-target space.

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Thesis (Ph.D.)--University of Western Australia, 2006.

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Orientador: Horatiu Stefan Nastase / Banca: Nathan Jacob Berkovits / Banca: Ever Aldo Arroyo Montero / Banca: Victor de Oliveira Rivelles / Banca: Ion Vasile Vancea / Resumo: Nessa tese estudamos propriedades de soluções de supergravidade tipo II obtidas através da dualidade T abeliana e não abeliana. Também determinamos, através da conjectura gauge/gravidade, aspectos da teoria de campos dual a essas soluções obtidas por dualidade T. Consideramos três tipos distintos de soluções: duais a teorias de campos que confinam, duais a teoria de campos conformes e duais a teoria de campos não-relativistas. Concluimos essa tese com uma análise dos laços de Wilson em soluções com simetria não relativista / Abstract: In this thesis we study properties of type II supergravity solutions generated by abelian and nonabelian T-duality. Also we determine, through the gauge/gravity conjecture, some aspects of the field theory dual to the supergravity solutions obtained by T-dualization. We consider three distinct types of backgrounds solutions, namely, backgrounds that are dual to confining field theories, backgrounds dual to conformal field theories and those dual to nonrelativistic field theories. We conclude this thesis with an analysis of Wilson loops on backgrounds with nonrelativistic symmetries / Doutor

<p> We look for time-dependent solutions to a general class of supergravity models in an arbitrary amount of dimensions. Previously, many static solutions of these models have been found and studied, of which a subclass of these solutions support membrane-like configurations. While many properties of these solutions are known, their dynamics - and therefore stability - are not. We follow this motivation, and investigate the possibility of time dependent solutions that will also support this membrane configuration. Under various conditions, it turns out this is the case, bringing a better understanding to the stability of these branes. In addition, the form of the time dependence found suggest possible applications of supergravity to cosmological models.</p> / Thesis / Master of Science (MSc)