Large Non-Gaussianity Implication for Curvaton Scenario

TL;DR

This paper explores the relationship between non-Gaussianity and the tensor-scalar ratio in the curvaton scenario, suggesting that large non-Gaussianity implies high inflation energy scales.

Contribution

It establishes a bound on the non-Gaussianity parameter based on the energy density of a light scalar field during inflation.

Findings

Non-Gaussianity parameter f_NL is bounded by the tensor-scalar ratio r.

Large non-Gaussianity (f_NL ~ 100) indicates inflation near the GUT scale.

Energy density of scalar fields during inflation should not be less than H^4.

Abstract

We argue that the typical energy density of a light scalar field should not be less than $H^4$ in the inflationary Universe. This requirement implies that the non-Gaussianity parameter $f_{NL}$ is typically bounded by the tensor-scalar ratio $r$ from above, namely $f_{NL}\lesssim 518\cdot r^{1\over 4}$. If $f_{NL}=10^2$, inflation occurred around the GUT scale.