Non-Gaussianity from Entanglement During Inflation

Abstract

We compute the bi-spectrum of CMB temperature fluctuations for a state where the metric perturbation $ζ$ is entangled with a spectator scalar field $χ$. Novel terms in the cubic $ζ$ 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.

17 pages, 7 figures