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Showing 1 to 20 of 173 for “"String theory"”.
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Topics in String Theory
Submitted by Meng Tao (mengtao2@illinois.edu) on 2012-10-19T19:21:42Z No. of bitstreams: 1 jejjala.pdf: 1292566 bytes, checksum: 491802881c252b3a04a08156556ce25b (MD5)
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Supersymmetric Backgrounds in string theory
… moduli, for a given background of type IIB string theory in the presence of flux in special cases. We introduce a way to compute the complex structure and axion dilaton moduli explicitly. In the second part, we discuss $(0,2)$ supersymmetric versions of some recent exotic $mathcal{N}=(2,2)$ …
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Obstacles to realizing Quintessence from String Theory
… models by flux compactification of type IIB string theory. We focus on Kähler moduli as candidates for the quintessence field and briefly comment on other approaches. The large hierarchies required for simultaneously describing quintessence and the standard model pose a major challenge to …
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Supersymmetry, supergravity, and String Theory based inflationary cosmology
… and present an overview of inflationary theory. As part of this effort, the main motivations for cosmic inflation, which are known as problems in the standard big bang scenario, are reviewed. These problems are the "flatness problem", "horizon problem", and the "monopole problem." …
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Aspects of branes and orbifolds in string theory
… theme of this thesis is branes and orbifolds in string theory, with some digression towards other directions in the final chapters. After reviewing background material on D-branes and orbifolds, along with some mathematical fundamentals, I describe the following results. First, a classification …
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On Vacuum Structures and Quantum Corrections in String Theory
… (EFTs) coupled to gravity. In this context, string theory has emerged as a viable candidate for a UV complete theory of quantum gravity. Its compactifications result in a landscape of string vacua encompassing an immensely rich and diverse structure of EFTs. Extracting reliable low energy …
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Lessons on interacting quantum field theories from string theory
In this thesis, we use string theory constructions and dualities to explore various features of interacting quantum field theories. We begin with an overview in Chapter 1, of past and recent developments in quantum field theories, explaining the advantages of string theoretic techniques over …
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Orbifold branes in string theory and their applications to cosmology.
… compactification schemes of 10-dimensional string theory, as well as some of the implications of one of these schemes for string cosmology. The first half of this work begins with a brief overview of cosmology and goes through constructing and then analyzing the first model, inspired by the …
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New Perspectives on Operator Deformations and T-duality in String Theory
The moduli space of string theories has been the subject of intense research efforts for many years now. Much of these efforts are focused on string compactifications, and in particular worldsheet conformal field theories (CFTs) embedded in toroidal target spaces. The CFTs defined at each point in …
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Vignettes in string theory : using geometry to probe the worldsheet and strongly coupled physics
… quasi-geometric flux vacua of the heterotic string. Second, we also investigate sigma models that break world-volume Lorentz invariance. Specifically, we calculate the one loop beta function for a target space metric whose worldvolume scales space and time differently, with dynamical exponent …
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Black holes and solitons in string theory and M-theory: a low energy limit analysis
… and higher-curvature corrections from superstring theory on black hole and soliton physics in different dimensions. The first order α ′−corrections derived from heterotic string theory, up to a field redefinition, lead to Einstein-dilaton-Gauss-Bonnet theory. We construct the first-order …
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String Theory and Our Relationship with Nature: The Convergence of Science, Curriculum Theory, and the Environment
Curriculum Theory affords us the opportunity to examine education from a multitude of directions. This work takes advantage of that opportunity to explore the relationships between science, nature, and curriculum using string theory and our ideas about the environment as a backdrop. Both the energy …
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Three lessons in causality : what string theory has to say about naked singularities, time travel and horizon complementarity
… branch of (2+1)-dimensional pure SU(N) gauge theory are extracted from the geometry. Related results for wrapped D4-- and D5-brane distributions are also discussed. Next, we turn to the issue of time travel. Many solutions of General Relativity appear to allow the possibility of time travel. …
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Higher Derivative Corrections to the Low-Energy E ective Action of Type IIA/B String Theory and M-theory
… low-energy eective theories of type IIA and IIB string theory. In addition, the unique eleven dimensional supergravity theory is the low-energy eective action of M-theory. Higher order corrections to the low-energy eective actions of these supergravity theories contain perturbative and …
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Aspects of String Compactification
… addresses some interesting problems in string compactification relevant to phenomenology, especially cosmological models derived from string theory Most attention is drawn to stabilizing the moduli and discussing the cosmology solutions given the effective potential obtained from string …
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Colliding branes and formation of spacetime singularities in superstring theory.
… is made, in the framework of 10-dimensional string theory. After developing the general formulas to describe such events, we study several classes of exact solutions and space-time singularities in both the (D+d)-dimensional string theory and its D-dimensional effective theory, obtained by …
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On Stability and Evolution of Solutions in General Relativity
… problems in general relativity and low energy string theory that are pertinent to the time evolution of the gravitational field. We present a formulation of the Einstein field equations in terms of variational techniques borrowed from geometric analysis. These equations yield the evolution …
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D-branes and K-homology
… group of the spacetime manifold $X$ of string theory and D-branes in string theory is examined. An element of the $K$-homology group is given by an equivalence class of $K$-cycles $[M,E,\phi]$, where $M$ is a closed spin$^c$ manifold, $E$ is a complex vector bundle over $M$, and $\phi: …
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