General Single Field Inflation with Large Positive Non-Gaussianity

TL;DR

This paper explores how general single field inflation models can produce large positive non-Gaussianity, specifically large equilateral $f_{NL}$, which is relevant for interpreting WMAP data.

Contribution

It demonstrates that non-conventional kinetic terms in single field inflation can generate large positive equilateral non-Gaussianity, expanding the class of viable inflation models.

Findings

Large positive $f_{NL}^{equil}$ can be achieved in single field inflation.

Models differ from ghost inflation with non-conventional kinetic terms.

Potential to explain WMAP observations of non-Gaussianity.

Abstract

Recent analysis of the WMAP three year data suggests $f_{NL}^{local}\simeq86.8$ in the WMAP convention. It is necessary to make sure whether general single field inflation can produce a large positive $f_{NL}$ before turning to other scenarios. We give some examples to generate a large positive $f_{NL}^{equil}$ in general single field inflation. Our models are different from ghost inflation. Due to the appearance of non-conventional kinetic terms, $f_{NL}^{equil}\gg1$ can be realized in single field inflation.