New natural shapes of non-Gaussianity from high-derivative interactions and their optimal limits from WMAP 9-year data

TL;DR

This paper explores unique non-Gaussian signatures from high-derivative inflationary models, introduces new templates for their detection, and analyzes WMAP 9-year data to find marginal evidence of non-zero signals.

Contribution

It identifies the need for two new templates to fully capture the non-Gaussian signatures of high-derivative inflation models and performs an optimal analysis on WMAP data.

Findings

Two new templates are necessary for complete coverage of model signatures.

WMAP 9-year data shows a 2-2.5 sigma hint of non-zero non-Gaussianity.

Preference for nonzero orthogonal non-Gaussianity in WMAP data.

Abstract

Given the fantastic experimental effort, it is important to thoroughly explore the signature space of inflationary models. The fact that higher derivative operators do not renormalize lower derivative ones allows us to find a large class of technically natural single-clock inflationary models where, in the context of the Effective Field Theory of Inflation, the leading interactions have many derivatives. We systematically explore the 3-point function induced by these models and their overlap with the standard equilateral and orthogonal templates. We find that in order to satisfactorily cover the signature space of these models, two new additional templates need to be included. We then perform the optimal analysis of the WMAP 9-year data for the resulting four templates, finding that the overall significance of a non-zero signal is between 2--2.5$\sigma$, depending on the choice of parameter space, partially driven by the preference for nonzero $f_{NL}^{\rm orth}$ in WMAP9.