Primordial Fluctuations in String Cosmology

This thesis is dedicated to the study of inflationary scenarios based on string theory. Inflation is a brief period of accelerated expansion in the very early Universe which gives natural explanations for problems of the Standard Big Bang Model (SBBM) of cosmology. The phenomenological success of inflation provides the motivation for numerous efforts to establish its connection with particle physics. As a promising contender for a unified theory at very high energy scales, string theory is an obvious framework to look for the theoretical foundations of inflation; we therefore try to determine the characteristic features of string-inspired inflationary scenarios, along with their observational consequences. In particular, we shall be interested in models of brane inflation, in which the inflaton field has non-canonical dymanics and where the era of reheating is interpreted as the mutual annihilation of (anti-)branes. This document contains an introduction to cosmology and string theory as well as the model building efforts untertaken at their intersection in recent years. The scientific articles published during the thesis are represented by a short summary each and are available separately on the arXiv