# Non-Gaussianity from Entanglement During Inflation

## TL;DR

This paper investigates how entanglement between metric perturbations and a spectator scalar field during inflation can produce distinctive non-Gaussian features in the CMB bi-spectrum, revealing new observational signatures.

## Contribution

It introduces a novel calculation of the bi-spectrum considering entangled states, highlighting new dominant terms and shapes absent in previous no-entanglement models.

## Key findings

- Entanglement leads to new dominant contributions in the bi-spectrum.
- Distinctive shapes in the bi-spectrum can serve as observational signatures.
- Entangled states modify the expected non-Gaussian features in the CMB.

## Abstract

We compute the bi-spectrum of CMB temperature fluctuations for a state where the metric perturbation $\zeta$ is entangled with a spectator scalar field $\chi$. Novel terms in the cubic $\zeta$ action coupled to the scalar can be the dominant contribution to the bi-spectrum for such states and we highlight the differences between this result and the no-entanglement bi-spectrum. New shapes can be important in the bi-spectra leading to distinctive observational signatures.