Resummation of Cosmological Correlators and their UV-Regularization

TL;DR

This paper develops a new UV-regularization method for cosmological correlators in de Sitter space, enabling resummation of higher loop diagrams and providing insights into non-perturbative effects.

Contribution

It introduces a de Sitter-invariant UV-regularization scheme that simplifies the resummation of higher loop diagrams in cosmological correlators.

Findings

Necklace topology diagrams do not resum with standard regularization.

The modified regularization allows resummation and reveals non-perturbative effects.

The approach aligns with recent cosmological dressing rules.

Abstract

Cosmological correlators are important observables in cosmology. They are often approximated by de Sitter space correlators. In this paper, we give a first precise diagrammatical computation of higher loop diagrams to all orders for a conformally coupled scalar in four dimensions. We show that, in contrast to flat space, diagrams of necklace topology do not resum using the natural application of de Sitter-invariant regularization and are thus hard to evaluate. We propose a modification to the UV-regularization of the loops, compatible with de Sitter invariance, but much easier to work with. The modified diagrams can be resummed to give a glimpse at non-perturbative effects for de Sitter correlators. Furthermore, they fit nicely with recently proposed cosmological dressing rules.