Cosmological correlation functions in scalar and vector inflationary models

TL;DR

This thesis investigates higher-order corrections to cosmological correlation functions, anisotropic inflation models with vector fields, and their observational signatures, aiming to better understand the early Universe through advanced theoretical calculations.

Contribution

It provides new calculations of loop corrections, bispectra, and trispectra in anisotropic and vector field inflation models, linking theory with upcoming precise data.

Findings

Computed scalar-tensor loop corrections in single-field inflation.

Analyzed statistical anisotropy in models with SU(2) vector fields.

Studied cosmological perturbations in Bianchi type-I universe.

Abstract

This thesis is centered on three main subjects within the theory of inflation and cosmological perturbations: loop corrections to the power spectrum of curvature fluctuations generated during inflation; evolution of cosmological fluctuations in anisotropic pre-inflationary cosmologies; statistical anisotropy and non-Gaussianity predictions of models of inflation populated with vector fields. Currently, what makes even more interesting the study of 2-nd and higher order corrections to cosmological correlation functions as well as the computation of higher-than-two order correlators, is the almost unprecedented chance to confront theories with new and increasingly accurate experimental data that will shed more light in the physics of the early Universe. In the context of loop calculations, we have computed the corrections arising from scalar-tensor interactions in models of single-field inflation (both for the standard slow-roll model and for models described by Lagrangians with non-canonical kinetic terms). In the context of anisotropic cosmologies, also motivated by the observation of "anomalies" in the Cosmic Microwave Background (CMB) fluctuations, we have computed the bispectrum and the trispectrum of the curvature fluctuations in inflationary models with SU(2) vector fields, analyzing the statistical anisotropy features of the correlators in these models; finally, we have studied cosmological perturbations for a Universe with a Bianchi type-I background metric, with an energy density dominated by a pressureless fluid and in the presence of a cosmological constant.