Non-Gaussianity and statistical anisotropy from vector field populated inflationary models

TL;DR

This review discusses vector field inflation models, focusing on SU(2) gauge groups, highlighting their unique predictions of statistical anisotropy and non-Gaussianity in primordial fluctuations, with detailed correlation function analyses.

Contribution

It provides a comprehensive review of non-Abelian vector inflation models, including analytic expressions for higher-order correlation functions and their implications for anisotropy and non-Gaussianity.

Findings

Vector fields can induce observable statistical anisotropy.

Non-Abelian models predict richer non-Gaussian signatures.

Anisotropic contributions may dominate in bispectrum and trispectrum.

Abstract

We present a review of vector field models of inflation and, in particular, of the statistical anisotropy and non-Gaussianity predictions of models with SU(2) vector multiplets. Non-Abelian gauge groups introduce a richer amount of predictions compared to the Abelian ones, mostly because of the presence of vector fields self-interactions. Primordial vector fields can violate isotropy leaving their imprint in the comoving curvature fluctuations zeta at late times. We provide the analytic expressions of the correlation functions of zeta up to fourth order and an analysis of their amplitudes and shapes. The statistical anisotropy signatures expected in these models are important and, potentially, the anisotropic contributions to the bispectrum and the trispectrum can overcome the isotropic parts.