Constructing and constraining models of inflation

As well as solving various problems with the hot Big Bang, cosmological inflation provides the most natural mechanism for generating the primordial fluctuations from which structures form. These fluctuations also lead to anisotropies in the Cosmic Microwave Background, which have been accurately measured by experiments such as Planck. Cosmological observations constrain the power spectra of primordial fluctuations over a relatively small range of large scales however. If the fluctuations on small scales are large they can collapse to form Primordial Black Holes (PBHs). The abundance of PBHs is tightly constrained by their evaporation and gravitational effects. PBHs therefore provide a potentially powerful additional constraint on the primordial power spectrum, and hence the dynamics of inflation. Current observations appear to favour simple single scalar field inflation models, however the particle physics underlying inflation is not yet understood. We will investigate a range of particle physics motivated inflation models. We will calculate the power spectra of both scalar and tensor perturbations, finding the parameters for which the models are consistent with current observations and also making predictions for future observations, for instance of B-mode polarisation. We will also investigate the constraints which arise from avoiding the overproduction of Primordial Black Holes.