Inflationary cosmology and fundamental physics

Abstract

This thesis is a collection of several papers at the interface between cosmology, particle physics, and field theory. In the first half, we examine topics that are directly related to inflation: axions, string theory, and non-minimally coupled fields. In particular, we constrain the allowed parameter space of inflationary axion cosmology, identifying a classic window and an anthropic window; we discuss inflation in string theory, proving a no-go theorem for a class of string models; and we examine the quantum field theory governing inflation driven by non-minimally coupled fields, which is relevant to Higgs-inflation. In the second half, we examine other topics: oscillons, entanglement entropy, and the Casimir effect. In particular, we compute the quantum decay of oscillons, finding it to be dramatically different to the classical decay; we establish finite contributions to the entanglement entropy between a pair of regions, including a finite area law; and we compute the Casimir force in a closed geometry, finding an attractive force and invalidating claims of repulsion.