Split Representations and Bubble Resummation for Massive de Sitter Correlators

TL;DR

This paper introduces a novel method combining spectral and split representations to efficiently compute multi-loop correlators in de Sitter space, enabling non-perturbative analysis of cosmological signals.

Contribution

It extends loop resummation techniques from flat to de Sitter space and allows direct identification of signal components at the integrand level.

Findings

Extended resummation of loop contributions to de Sitter space.

Identified signal parts directly from the spectral function.

Applied method to analyze non-perturbative EFT flow and collider signals.

Abstract

We combine spectral- and split representations to factorize multi-loop momentum space diagrams, in the Schwinger-Keldysh formulation for cosmological correlators, with massive scalars in the loop. This allows us to extend the resummation of loop contributions from flat to de Sitter space. Furthermore, in our split representation the signal part of the correlators can be identified directly on the integrand level from the spectral function. We apply this to describe the non-perturbative flow of the EFT background and the cosmological collider signals in a large-N model.