Cosmology driven by physics beyond the standard model

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Title: Cosmology driven by physics beyond the standard model
Author: Žanić, Marija, 1972-
Abstract: This dissertation investigates several problems inspired by the interplay of cosmology and theories beyond the Standard Model of particle physics . The first part of this work is a study of time evolution of unstable dS[subscript p] x S[superscript q] configurations with flux in theories of gravity with a cosmological constant . We find that , depending on the flux , these configurations either evolve towards newly identified stable solutions with a smaller final effective cosmological constant , or tend toward decompactication of the internal sphere . In the second part , we investigate the problem of evolution of vacuum bubbles in inhomogeneous backgrounds . It is expected that the process of inflation will signifcantly smooth out spatial inhomogeneities . However , the initial conditions for inflation are often taken in the already homogeneous and isotropic FRW form , even though it is assumed that initial homogeneity is not necessary for the onset of inflation . We determine the effects of certain inhomogeneities , introduced in the curvature of the outside spacetime , on the propagation of bubbles , and how these effects differ depending on whether the perspective taken is that of the outside observer or an observer on the bubble . The last part of the dissertation presents a model for a novel component of the energy density of the universe . The observational limits on the present energy density allow for a component that redshifts like 1 /a² and can contribute significantly to the total . We show that one possible origin for such a contribution is that the universe has a toroidal topology with "wound" scalar fields around its cycles .
URI: http : / /hdl .handle .net /2152 /3708
Date: 2008-08-29


Cosmology driven by physics beyond the standard model. Doctoral dissertation, The University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /3708 .

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