2009/11/14 by Rhiannon Gwyn, Gwyn, Rhiannon
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Particle physics theoretical and experimental studies #hep-th
paper · pdf · doi:10.48550/arxiv.0911.2782
152 pages, 17 figures, 2 tables. PhD thesis
arxiv created 2009/11/14 · openalex publication_date 2009/11/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The intersection of string theory with cosmology is unavoidable in the early universe, and its exploration may shine light on both fields. In this thesis, three papers at this intersection are presented and reviewed, with the aim of providing a thorough and pedagogical guide to their results. First, we address the longstanding problem of finding a string theory realisation of the axion. Using warped compactifications in heterotic string theory, we show that the axion decay constant can be lowered to acceptable values by the warp factor. Next, we move to the subject of cosmic strings, whose network evolution could have important consequences for astrophysics and cosmology. In particular, there are quantitative differences between cosmic superstring networks and GUT cosmic string networks. We investigate the properties of cosmic superstring networks in warped backgrounds, giving the tension and properties of three-string junctions in these backgrounds. Finally, we examine the possibility that cosmic strings in heterotic string theory could be responsible for generating the galactic magnetic fields that seeded those observed today.