Non-Gaussianity from resonant curvaton decay

TL;DR

This paper investigates how resonant decay of the curvaton field into another scalar field leads to highly non-Gaussian curvature perturbations, using lattice simulations to capture nonlinear effects beyond standard perturbative methods.

Contribution

The study introduces a lattice simulation approach to analyze nonlinear curvature perturbations from resonant curvaton decay, revealing significant non-Gaussian features.

Findings

Perturbations are highly non-Gaussian in the resonant decay scenario.

Standard fNL parameterization does not adequately describe the perturbations.

Resonant decay significantly impacts the curvature perturbation spectrum.

Abstract

We calculate curvature perturbations in the scenario in which the curvaton field decays into another scalar field via parametric resonance. As a result of a nonlinear stage at the end of the resonance, standard perturbative calculation techniques fail in this case. Instead, we use lattice field theory simulations and the separate universe approximation to calculate the curvature perturbation as a nonlinear function of the curvaton field. For the parameters tested, the generated perturbations are highly non-Gaussian and not well approximated by the usual fNL parameterisation. Resonant decay plays an important role in the curvaton scenario and can have a substantial effect on the resulting perturbations.