Enhanced local-type inflationary trispectrum from a non-vacuum initial state

TL;DR

This paper calculates the primordial trispectrum during inflation with a non-vacuum initial state, revealing enhanced local-type signals that could be detectable by future observations, surpassing standard predictions.

Contribution

It introduces a method to compute the inflationary trispectrum with non-vacuum initial states, showing significant enhancement in local configurations compared to standard models.

Findings

Enhanced trispectrum amplitude in squeezed configurations.

Amplitude can exceed Maldacena's prediction by a factor of 10^6.

Potential detectability with upcoming observational data.

Abstract

We compute the primordial trispectrum for curvature perturbations produced during cosmic inflation in models with standard kinetic terms, when the initial quantum state is not necessarily the vacuum state. The presence of initial perturbations enhances the trispectrum amplitude for configuration in which one of the momenta, say $k_3$, is much smaller than the others, $k_3 \ll k_{1,2,4}$. For those squeezed configurations the trispectrum acquires the so-called local form, with a scale dependent amplitude that can get values of order $ \epsilon ({k_1}/{k_3})^2$. This amplitude can be larger than the prediction of the so-called Maldacena consistency relation by a factor $10^6$, and can reach the sensitivity of forthcoming observations, even for single-field inflationary models.