Mohammad Hossein Namjoo

Violation of non-Gaussianity consistency relation in a single-field inflationary model

In this paper we present a simple, toy model of single-field inflation in which the standard non-Gaussianity consistency condition is violated. In this model the curvature perturbations on super-horizon scales are not conserved and the decaying modes of perturbations are not negligible in the non-attractor phase. As a result a large local non-Gaussianity can be obtained in the squeezed limit which violates the standard non-Gaussianity consistency condition for the single-field models.

A Single Field Inflation Model with Large Local Non-Gaussianity

The detection of a large local form of non-Gaussianity is considered to be able to rule out all single field inflation models. This statement is based on the single field consistency condition. Despite the awareness of some implicit assumptions in the derivation of this condition and the demonstration of corresponding examples that illustrate these caveats, to date there is still no explicit and self-consistent model which can serve as a counterexample to this statement. We present such a model in this letter.

Hemispherical Asymmetry and Local non-Gaussianity: a Consistency Condition

In this paper we provide a consistency relation between the amplitude of the hemispherical bipolar asymmetry,

Asymmetric Sky from the Long Mode Modulations

A

In-in and

, and the amplitude of the primordial non-Gaussianity in the squeezed limit,

\delta N

{f}_{NL}

calculations of the bispectrum from non-attractor single-field inflation

, as

Modulated curvaton decay

|A|\ensuremath{\lesssim}{10}^{\ensuremath{-}1}{f}_{NL}

Curvature perturbations and non-Gaussianities from the waterfall phase transition during inflation

. We demonstrate that this consistency condition is at work for any model of inflation in which the curvature perturbations are sourced by a single light field with the Bunch\char21{}Davies initial condition, irrespective of the number of inflation fields that contribute to the background inflationary expansion. As a nontrivial example, we show that observable hemispherical asymmetry can be generated in single-field nonattractor inflationary models. We also study hemispherical asymmetry generated in the models of multiple fields inflation. We show that

Models of the Primordial Standard Clock

A