Strongly scale-dependent polyspectra from curvaton self-interactions

TL;DR

This paper investigates how self-interactions in curvaton models cause strong scale dependence in non-linearity parameters, potentially observable by Planck, and discusses how these features can constrain or falsify the models.

Contribution

It demonstrates that self-interactions lead to large spectral indices for f_NL and g_NL, revealing new observable signatures and constraints in curvaton models.

Findings

Spectral indices n_fNL and n_gNL can exceed slow-roll parameters.

Scale dependence of f_NL and g_NL is potentially observable by Planck.

Model can be falsified if g_NL(k) is measured.

Abstract

We study the scale dependence of the non-linearity parameters f_NL and g_NL in curvaton models with self-interactions. We show that the spectral indices n_fNL=d ln|f_NL|/(d ln k) and n_gNL=d ln |g_NL|/(d ln k) can take values much greater than the slow--roll parameters and the spectral index of the power spectrum. This means that the scale--dependence of the bi and trispectrum could be easily observable in this scenario with Planck, which would lead to tight additional constraints on the model. Inspite of the highly non-trivial behaviour of f_NL and g_NL in the curvaton models with self-interactions, we find that the model can be falsified if g_NL(k) is also observed.