Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 150-160). Available also in a digital version from Dissertation Abstracts.

Orientifolds of type II string theory offer a promising toolkit for model builders, especially when one includes not only the usual fluxes from NSNS and RR field strengths, but also fluxes that are T-dual to the NSNS three-form flux. These additional ingredients can help stabilize moduli and lead to D-term contributions to the effective scalar potential. We describe in general how these fluxes appear as parameters of an effective N = 1 supergravity theory in four dimensions for type IIA and type IIB string theory. We also show how these fluxes arise from compactifications on six-dimensional spaces that can be described by toroidal fibers twisted over a toroidal base. This approach leads us to a more subtle treatment of the quantization of the general NSNS fluxes. We illustrate these phenomena with examples of certain orientifolds of T⁶/Z₄. / text

In this Ph.D. thesis, we construct and study a number of new type IIB supergravity backgrounds that realize various flavored, finite temperature, and non-supersymmetric deformations of the resolved and deformed conifold geometries. We make heavy use of a U-duality solution generating procedure that allows us to begin with a modification of a family of solutions describing the backreaction of D5 branes wrapped on the S^2 of the resolved conifold, and generate new backgrounds related to the Klebanov-Strassler background. We first construct finite temperature backgrounds which describe a configuration of N_c D5 branes wrapped on the S^2 of the resolved conifold, in the presence of N_f flavor brane sources and their backreaction i.e. N_f/N_c ~ 1. In these solutions the dilaton does not blow up at infinity but stabilizes to a finite value. The U-duality procedure is then applied to these solutions to generate new ones with D5 and D3 charge. The resulting backgrounds are a non-extremal deformation of the resolved deformed conifold with D3 and D5 sources. It is tempting to interpret these solutions as gravity duals of finite temperature field theories exhibiting phenomena such as Seiberg dualities, Higgsing and confinement. However, a first necessary step in this direction is to investigate their stability. We study the specific heat of these new flavored backgrounds and find that they are thermodynamically unstable. Our results on the stability also apply to other non-extremal backgrounds with Klebanov-Strassler asymptotics found in the literature. In the second half of this thesis, we apply the U-duality procedure to generate another class of solutions which are zero temperature, non-supersymmetric deformations of the baryonic branch of Klebanov-Strassler. We interpret these in the dual field theory by the addition of a small gaugino mass. Using a combination of numerical and analytical methods, we construct the backgrounds explicitly, and calculate various observables of the field theory. / text

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We develop a general computational model for a elastic rod which allows for extension and shear. / Physics

The fluid/gravity correspondence relates solutions of the incompressible Navier-Stokes equation to metrics which solve the Einstein equations. We propose propose two possible approaches to establish this correspondence: perturbative expansion for shear modes and large mean curvature expansion for algebraically special metrics. / Physics

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Aaron Copland's Clarinet Concerto was written for jazz clarinetist Benny Goodman. The work's incorporation of popular elements, particularly jazz, has led to the perception that it is a "lightweight" representative of Copland's output. However, the concerto shares many characteristics with French neoclassical works of the 1920's and SCfs, and demonstrates a highly skilled construction that belies this label. The neoclassical aspect of the concerto raises important questions as to whether the jazz elements in the piece are really central to its expressive essence, or whether they merely reflect a choice of materials common to Copland and to other neoclassical composers. This dissertation is directed to the potential performer who wishes to have a better knowledge of the concerto's performance issues. It discusses the influence of neoclassicism on Copland's compositional style, gives the historical background to the Clarinet Concerto's composition, and outlines its general stylistic characteristics. The concerto's structure is examined in detail, and then applied to the work's performance issues, as the document investigates the performance practice of the piece through the study of recordings. The purpose of this dissertation is not to burden performers with a detailed set of instructions to be followed in performing the concerto. Rather, it aims to equip them with the techniques necessary to developing an individual, personal interpretation, based on a thorough understanding of the piece.

Aaron Copland's Clarinet Concerto was written for jazz clarinetist Benny Goodman. The work's incorporation of popular elements, particularly jazz, has led to the perception that it is a "lightweight" representative of Copland's output. However, the concerto shares many characteristics with French neoclassical works of the 1920's and SCfs, and demonstrates a highly skilled construction that belies this label. The neoclassical aspect of the concerto raises important questions as to whether the jazz elements in the piece are really central to its expressive essence, or whether they merely reflect a choice of materials common to Copland and to other neoclassical composers. This dissertation is directed to the potential performer who wishes to have a better knowledge of the concerto's performance issues. It discusses the influence of neoclassicism on Copland's compositional style, gives the historical background to the Clarinet Concerto's composition, and outlines its general stylistic characteristics. The concerto's structure is examined in detail, and then applied to the work's performance issues, as the document investigates the performance practice of the piece through the study of recordings. The purpose of this dissertation is not to burden performers with a detailed set of instructions to be followed in performing the concerto. Rather, it aims to equip them with the techniques necessary to developing an individual, personal interpretation, based on a thorough understanding of the piece.

This work aims to understand how cosmic inflation embeds into larger models of particle physics and string theory. Our work operates within a weakened version of the Landscape paradigm, wherein it is assumed that the set of possible Lagrangians is vast enough to admit the notion of a generic model. By focusing on slow-roll inflation, we examine the roles of both the scalar potential and the space of couplings which determine its precise form. In particular, we focus on the structural properties of the scalar potential, and find a surprising result: inflection point inflation emerges as an important —and under certain assumptions, dominant — possibility in the context of generic scalar potentials. We begin by a systematic coarse graining over the set of possible inflection point inflation models using V.I. Arnold’s ADE classification of singularities. Similar to du Val’s pioneering work on surface singularities, these determine structural classes for inflection point inflation which depened on a distinct number of control parameters. We consider both single and multifield inflation, and show how the various structural classes embed within each other. We also show how such control parameters influence the larger physical models in to which inflation is embedded. These techniques are then applied to both MSSM inflation and KKLT-type models of string cosmology. In the former case, we find that the scale of inflation can be entirely encoded within the super- potential of supersymmetric quantum field theories. We show how this relieves the fine-tuning required in such models by upwards of twelve orders of magnitude. Moreover, unnatural tuning between SUSY breaking and SUSY preserving sectors is eliminated without the explicit need for any hidden sector dynamics. In the later case, we discuss how structural stability vastly generalizes — and addresses — the Kallosh-Linde problem. Implications for the spectrum of SUSY breaking soft terms are then discussed, with an emphasis on how they may assist in constraining the inflationary scalar potential. We then pivot to a general discussion of the FLRW-scalar phase space, and show how inflection points induce caustics — or dynamical fixed points — amongst the space of possible trajectories. These fixed points are then used to argue that for uninformative priors on the space of couplings, the likelihood of inflection point inflation scales with the inverse cube of the number of e-foldings. We point out the geometric origin for the known ambiguity in the Liouville measure, and demonstrate of inflection point inflation ameliorates this problem. Finally we investigate the effect of the fixed point structure on the spectrum of density perturbations. We show how an anomaly in the Cosmic Mircowave Background data — low power at large scales — can be explained as a by product of the fixed point dynamics.