Non-Gaussian signatures in a string-inspired model for the onset of inflation.

Supersymmetry breaking is a key ingredient to connect String Theory to the observed Universe. "Brane Supersymmetry Breaking" is possibly the simplest and most natural scenario available to this end, since it results when the vacuum contains different extended objects (branes and orientifolds) that preserve different portions of supersymmetry. This avoids tachyon instabilities and leaves, at low energies, a steep exponential potential that forces a scalar field to emerge from the initial singularity while climbing it up (Dudas, Kitazawa & Sagnotti 2010). In the presence of suitable corrections, this dynamics can inject an inflationary phase, while also inducing a depression of the primordial power spectrum of curvature perturbations on the largest cosmological scales, which can translate into a lack of power for the first few multipoles of the Cosmic Microwave Background (CMB) anisotropies. The aim of this master thesis is to perform an analytical study of the curvature perturbation bispectrum in this type of setting, which can provide further testable predictions of the model. This will entail a few technical advances, including a proper extension of the bispectrum analysis beyond slow roll. Possible connections of the resulting signatures with some of the so called "CMB anomalies" will also be discussed.