Aspects of inflation beyond the single-field, slow-roll regime

In this thesis, we explore two departures from the single field, slow-roll paradigm of inflation. The first part is dedicated to warm inflation. We revisit the theory of linear perturbations in this framework, develop computational techniques for the calculation of the primordial power spectrum and apply them to the analysis of CMB constraints and the production of primordial black holes. The second part focuses on the primordial non-Gaussianity arising from a phase of ultra slow-roll during single field inflation. We study the scope and limitations of the classical delta N formalism as a probe of such non-Gaussianity and determine the extent of its correspondence with the stochastic delta N formalism.

Supervisor: Guillermo Ballesteros Martínez