White Rose University Consortium logo
University of Leeds logo University of Sheffield logo York University logo

Studies of inflation and dark energy with coupled scalar fields

Vu, Susan (2014) Studies of inflation and dark energy with coupled scalar fields. PhD thesis, University of Sheffield.

[img]
Preview
Text
thesis_svu_corr.pdf
Available under License Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 UK: England & Wales.

Download (1078Kb) | Preview

Abstract

Currently there is no definitive description for the accelerated expansion of the Universe at both early and late times; we know these two periods as the epochs of inflation and dark energy. Contained within this Thesis are two studies of inflation and one in the context of dark energy. The first study involves two noncanonical kinetic terms each in a two-field scenario, and their effects on the generation of isocurvature modes. As a result, these terms affect the isocurvature perturbations produced, and consequently the Cosmic Microwave Background. In the following study, the impact of a sharp transition upon the effective Planck mass is considered in both a single-field and two-field model. A feature in the primordial power spectrum arising from these transitions is found in single-field models, but not for two-field models. The final model discussed is on the subject of dark energy. A type of nonconformal coupling is examined namely the “disformal” coupling; in this scenario a scalar field is disformally coupled to matter species. Two consistency checks are undertaken, the first to provide a fluid description and the second, a kinetic theory. From this, observables are constructed and used to create constraints on the individual coupling strengths.

Item Type: Thesis (PhD)
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield)
Identification Number/EthosID: uk.bl.ethos.631446
Depositing User: Susan Vu
Date Deposited: 11 Dec 2014 15:57
Last Modified: 03 Oct 2016 11:18
URI: http://etheses.whiterose.ac.uk/id/eprint/7418

Actions (repository staff only: login required)