Constructing Regularized Cosmic Propagators

TL;DR

This paper introduces a new scheme for calculating cosmic propagators that seamlessly connect low-k perturbative results with high-k resummed behavior, applicable to various cosmological models and validated against simulations.

Contribution

A novel, general method for computing multi-point cosmic propagators that interpolates between perturbative and resummed regimes, including non-standard cosmologies.

Findings

Good agreement with previous prescriptions and simulations

Effective for calculating matter bispectrum at one-loop order

Applicable to non-Gaussian initial conditions

Abstract

We present a new scheme for the general computation of cosmic propagators that allow to interpolate between standard perturbative results at low-k and their expected large-k resummed behavior. This scheme is applicable to any multi-point propagator and allows the matching of perturbative low-k calculations to any number of loops to their large-k behavior, and can potentially be applied in case of non-standard cosmological scenarios such as those with non-Gaussian initial conditions. The validity of our proposal is checked against previous prescriptions and measurements in numerical simulations showing a remarkably good agreement. Such a generic prescription for multi-point propagators provides the necessary building blocks for the computation of polyspectra in the context of the so-called Gamma-expansion introduced by Bernardeau et al. (2008). As a concrete application we present a consistent calculation of the matter bispectrum at one-loop order.