Non-minimally coupled vector curvaton

TL;DR

This paper demonstrates that a non-minimally coupled massive vector field can serve as a curvaton, generating curvature perturbations post-inflation without large-scale anisotropy, and explores the model's parameter space.

Contribution

It introduces a novel vector curvaton model with non-minimal gravity coupling and thoroughly analyzes its parameter constraints.

Findings

Vector boson can generate curvature perturbations after inflation

Model bounds on inflation scale and decay constant are established

No large-scale anisotropy is produced by the vector curvaton

Abstract

It is shown that a massive Abelian vector boson field can generate the curvature perturbation in the Universe, when coupled non-minimally to gravity, through an RA^2 coupling. The vector boson acts as a curvaton field imposing the curvature perturbation after the end of inflation, without generating a large-scale anisotropy. The parameter space of the model is fully explored, obtaining the relevant bounds on the inflation scale and the decay constant of the vector curvaton.