Passive Curvaton

TL;DR

This paper introduces passive curvaton models involving pseudoscalar and dilaton-like scalar fields coupled to gauge fields, which can generate significant non-Gaussianity with weaker primordial black hole constraints.

Contribution

It proposes new passive curvaton models with gauge field couplings, analyzing their non-Gaussianity and scale dependence, expanding the landscape of curvaton scenarios.

Findings

Large non-Gaussianity can be produced without strong PBH constraints.

Spectrum and non-Gaussianity are enhanced by the slow-roll parameter.

Scale dependence of non-Gaussianity is investigated.

Abstract

We propose a class of curvaton models which we call passive curvaton. In this paper, two kinds of passive curvaton is considered. The first one is a pseudoscalar curvaton couples to a gauge field. Different from the inflaton case, the constraint from formation of primordial black holes (PBHs) is much weaker and large non-gaussianity (of the equiliteral type) can be produced. The second model is a dilaton-like scalar curvaton couples to a gauge field. We investigate the scale dependence of non-gaussianity in this model. In both models, the spectrum and non-Gaussianity are enhanced by the slow-roll parameter of the curvaton field. Other possible passive curvaton models are also mentioned.