A search for transient reductions in the inflaton speed of sound in cosmological data, and other topics

Torrado Cacho, J. (2015)

Doctoral Thesis

This thesis consists of two different parts, separating research projects carried out in two different groups. In the first and longest part of this thesis, we attempt to fit the signal for a reduction in the speed of sound of the inflaton. In chapter 1, we shortly introduce the topics discussed in this thesis, namely _CDM cosmology, transient reductions in the speed of sound during inflation, and Bayesian statistical inference. Afterwards, we attempt to fit a particular hypothesis for the speed of sound reduction using Cosmic Microwave Background data (chapter 2) and later adding Large Scale Structure data to the search (chapter 3). Finally, in chapter 4 we present two pieces of code that were elaborated for the research in this thesis, and later released to the community. In the second part, consisting solely of chapter 5, we present a classification of all possible 6-dimensional symmetric toroidal orbifolds over which Heterotic String Theory leads to a supersymmetric model. To do that, we made use of standard crystallographic tools.

• Inflation
• CMB speed sound reduction
• Bispectrum
• Heterotic string orbifold
• EFT

• All authors: Torrado Cacho, J.
• Supervisor: Achúcarro, A.
• Committee: Lesgourges, J.; Zavala, E.I.; Pajer, E.; Eliel, E.R.; Schalm, K.E.; Valkenburg, W.
• Qualification: Doctor (dr.)
• Awarding Institution: Leiden Institute of Physics (LION), Faculty of Science, Leiden University
• Date: 2015-03-31
• Title of host publication: Casimir PhD Series
• ISBN (print): 9789085932123
• Name: 2015-4