Inflation from a simple model based on Weyl invariance

Abstract

Despite the many successes of the big bang model of the universe, it lacks the power to explain some key features of the universe including the fact that it is homogeneous, isotropic and spatially flat. A possible explanation of these are given by inflation, a short period before the onset of standard big bang evolution during which the universe expanded exponentially. This thesis starts with an introduction to single field inflation models and explains how they produce primordial fluctuations and then calculates their power spectrum, which can be observed in the cosmic microwave background. Following this discussion, a model based on conformal gravity and conformal coupling of a scalar field is introduced. The tensor and vector perturbations in this model are discussed both classically and quantum mechanically and their power spectra are calculated and are found to share key features with the power spectra of single field inflation.