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Nonlinear emergent complexity during cosmological symmetry breaking

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Call No.	QC45.N43 D3 2012sta
Author	Stamatopoulos, Nikitas.
Title	Nonlinear emergent complexity during cosmological symmetry breaking
Date	2012
Abstract	In this thesis, the dynamics of long-lived, time-dependent, coherent field configurations, known as oscillons, are investigated in the presence of an expanding background. In a (1+1)-dimensional expanding spacetime, scalar-field oscillon lifetimes are shown to be exponentially large compared to the natural time scales of the system. Moreover, a numerical investigation starting from (quasi) thermal initial conditions, indicates that a large fraction of the energy density of the Universe is taken up by oscillons, suggesting that they could play a role during various non-linear processes in the early Universe. Moving to (3+1) dimensions, a similar analysis is carried out in a symmetry breaking scenario in de Sitter space to examine how the rate of expansion affects oscillon lifetimes in a spherically symmetric model. Starting with thermal initial conditions similar to the (1+1)-dimensional case, oscillons are still found to occupy a significant fraction of the final energy density. Finally, a new class of two-field oscillons is studied which exhibit lifetimes as much as four times larger than the single-field oscillon solutions. Using parameters consistent with WMAP 7-year data, their emergence after hybrid inflation is investigated to reveal that oscillons end up contributing up to 20% to the final energy density of a matter-dominated Universe.
Description	viii, 93 leaves : ill. (some col.) ; 28 cm.
Format	application/pdf
Advisor	Gleiser, Marcelo; Caldwell, Robert; Blencowe, Miles; Graham, Noah
College	Dartmouth College -- Department of Physics and Astronomy.
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Copyright	All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means without permission in writing from the author.
DOI	http://dx.doi.org/10.1349/ddlp.448

Title	Page 1
Format	application/pdf
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Full Text	Nonlinear Emergent Complexity during Cosmological Symmetry Breaking A Thesis Submitted to the Faculty in partial ful llment of the requirements for the degree of Doctor of Philosophy in Physics and Astronomy by Nikitas Stamatopoulos DARTMOUTH COLLEGE Hanover, New Hampshire May 15, 2012 Examining Committee (Chair) Marcelo Gleiser Robert Caldwell Miles Blencowe Noah Graham Brian W. Pogue, Ph.D Dean of Graduate Studies

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