Resolving primordial physics through correlated signatures

TL;DR

This paper proposes using correlations among spectral observables to differentiate primordial perturbation models, revealing that specific signatures like spectral index running are linked to non-Gaussianity properties, which can distinguish inflationary scenarios.

Contribution

It introduces a novel method of analyzing correlations among spectral observables to identify the origin of primordial perturbations, especially distinguishing isocurvature from inflaton models.

Findings

Large spectral index running correlates with large $f_{NL}$ and $g_{NL}$.

A large negative running transitions to positive on smaller scales if tensor-to-scalar ratio is large.

The transition scale can differentiate between inflaton and isocurvature fields.

Abstract

We discuss correlations among spectral observables as a new tool for differentiating between models for the primordial perturbation. We show that if generated in the isocurvature sector, a running of the scalar spectral index is correlated with the statistical properties of non-Gaussianities. In particular, we find a large running will inevitably be accompanied by a large running of $f_{\rm NL}$ and enhanced $g_{\rm NL}$, with $g_{\rm NL}\gg f_{\rm NL}^2$. If the tensor to scalar ratio is large, a large negative running must turn positive on smaller scales. Interestingly, the characteristic scale of the transition could potentially distinguish between the inflaton and isocurvature fields.