From quantum fluctuations in the Early Universe to classical structures on cosmological scales.

Inflation models of the Early Universe provide the standard scenario for the origin of cosmic structures in the Universe, arising from microscopic quantum fluctuations, in accordance with a series of cosmological observations spanning a wide range of scales. Still, since the first days of Inflation, it was clear that it is necessary a mechanism to classicalize such fluctuations to give rise to the classical structures they give origin to and that we see in our observable Universe (such as galaxies, clusters of galaxies, temperature Cosmic Microwave Background anisotropies). The thesis will focus on (some of) the mechanisms proposed so far, with the main goal of possibly study new theoretical predictions that could help to characterise such mechanisms in terms of specific observational signatures.