Non-Gaussianity and Baryonic Isocurvature Fluctuations in the Curvaton Scenario

TL;DR

This paper analyzes how non-Gaussianity and baryonic isocurvature fluctuations arise in the curvaton scenario, showing that large non-Gaussianity can coexist with current observational constraints.

Contribution

It provides a detailed calculation of non-linearity parameter f_NL and baryonic isocurvature fluctuations considering both inflaton and curvaton primordial fluctuations.

Findings

Large non-Gaussianity (f_NL ~ 10-100) is possible without violating isocurvature constraints.

Baryonic isocurvature fluctuations can be generated unless baryogenesis occurs after curvaton decay.

Current observational constraints are severe but still compatible with significant non-Gaussianity.

Abstract

We discuss non-Gaussianity and baryonic isocurvature fluctuations in the curvaton scenario, assuming that the baryon asymmetry of the universe originates only from the decay products of the inflaton. When large non-Gaussianity is realized in such a scenario, non-vanishing baryonic isocurvature fluctuations can also be generated unless the baryogenesis occurs after the decay of the curvaton. We calculate the non-linearity parameter f_NL and the baryonic isocurvature fluctuations, taking account of the primordial fluctuations of both the inflaton and the curvaton. We show that, although current constraints on isocurvature fluctuations are severe, the non-linearity parameter can be large as f_NL \sim O(10-100) without conflicting with the constraints.