Holographic predictions for cosmological 3-point functions

TL;DR

This paper uses holographic duality to predict cosmological 3-point functions involving scalar and tensor modes, computing them at 1-loop order in a non-gravitational QFT and analyzing their shapes compared to slow-roll models.

Contribution

It provides the first holographic predictions for cosmological 3-point correlators involving both scalar and tensor modes, including explicit 1-loop calculations and shape analysis.

Findings

Holographic correlators are uniquely determined by Ward identities.

Some holographic bispectrum shapes are distinguishable from slow-roll predictions.

The analysis includes a comprehensive comparison of shapes for scalar and tensor modes.

Abstract

We present the holographic predictions for cosmological 3-point correlators, involving both scalar and tensor modes, for a universe which started in a non-geometric holographic phase. Holographic formulae relate the cosmological 3-point functions to stress tensor correlation functions of a holographically dual three-dimensional non-gravitational QFT. We compute these correlators at 1-loop order for a theory containing massless scalars, fermions and gauge fields, and present an extensive analysis of the constraints due to Ward identities showing that they uniquely determine the correlators up to a few constants. We define shapes for all cosmological bispectra and compare the holographic shapes to the slow-roll ones, finding that some are distinguishable while others, perhaps surprisingly, are not.