Statistical Anisotropy and the Vector Curvaton Paradigm

TL;DR

The paper reviews the vector curvaton paradigm, highlighting how massive vector fields can generate statistical anisotropy in the universe's curvature perturbations, with potential observational signatures and implications for beyond-standard-model physics.

Contribution

It analyzes specific models for superhorizon spectra of Abelian vector fields and discusses their observational signatures as vector curvatons.

Findings

Vector bosons can contribute to curvature perturbations.

Models predict statistical anisotropy in the spectrum and bispectrum.

Future observations could confirm the vector curvaton mechanism.

Abstract

The vector curvaton paradigm is reviewed. The mechanism allows a massive vector boson field to contribute to or even generate the curvature perturbation in the Universe. Contribution of vector bosons is likely to generate statistical anisotropy in the spectrum and bispectrum of the curvature perturbation, which will soon be probed observationally. Two specific models for the generation of superhorizon spectra for the components of an Abelian vector field are analysed. Emphasis is put on the observational signatures of the models when the vector fields play the role of vector curvatons. If future observations support the vector curvaton mechanism this will open a window into the gauge field content of theories beyond the standard model.