Non-Gaussianity with Lagrange Multiplier Field in the Curvaton Scenario

TL;DR

This paper investigates the effects of a Lagrange multiplier field on non-Gaussianity in the curvaton model, revealing that significant non-Gaussianity can occur even when the curvaton dominates before decay, enriching the model's phenomenology.

Contribution

It introduces a novel analysis of the curvaton scenario with a Lagrange multiplier field, calculating non-linearity parameters and probability distributions within this framework.

Findings

Large non-Gaussianity possible even with curvaton dominance

Calculated non-linearity parameters $f_{NL}$ and $g_{NL}$

Derived probability density function and moments of curvature perturbation

Abstract

In this paper, we will use $\delta \mathcal{N}$-formalism to calculate the primordial curvature perturbation for the curvaton model with a Lagrange multiplier field. We calculate the non-linearity parameters $f_{NL}$ and $g_{NL}$ in the sudden-decay approximation in this kind of model, and we find that one could get a large non-Gaussinity even if the curvaton dominates the total energy density before it decays, and this property will make the curvaton model much richer. We also calculate the probability density function of the primordial curvature perturbation in the sudden-decay approximation, as well as some moments of it.