Non-Gaussianity from Baryon Asymmetry

TL;DR

This paper explores how the baryon asymmetry of the universe, particularly via the Affleck-Dine mechanism, can produce significant non-Gaussian features in curvature perturbations, consistent with observational constraints.

Contribution

It demonstrates that the Affleck-Dine mechanism can generate large non-Gaussianity in curvature perturbations while satisfying baryonic isocurvature constraints.

Findings

Large non-Gaussianity can originate from baryon asymmetry.

The sign of f_{NL} depends on the baryogenesis scenario.

Constraints on isocurvature perturbations are satisfied.

Abstract

We study a scenario that large non-Gaussianity arises from the baryon asymmetry of the Universe. There are baryogenesis scenarios containing a light scalar field, which may result in baryonic isocurvature perturbations with some amount of non-Gaussianity. As an explicit example we consider the Affleck-Dine mechanism and show that a flat direction of the supersymmeteric standard model can generate large non-Gaussianity in the curvature perturbations, satisfying the observational constraints on the baryonic isocurvature perturbations. The sign of a non-linearity parameter, f_{NL}, is negative, if the Affleck-Dine mechanism accounts for the observed baryon asymmetry; otherwise it can be either positive or negative.