A Lagrangian effective field theory

TL;DR

This paper advances Lagrangian cosmological perturbation theory by integrating effective field theory, introducing a new resummation scheme, and comparing results with simulations, improving understanding of large-scale structure modeling.

Contribution

It formulates EFT within the Lagrangian framework and proposes a new resummation scheme, enhancing the modeling of matter density correlators in cosmology.

Findings

Models perform well above 2-3 times the non-linear scale

Lagrangian EFT matches Eulerian EFT at low redshift

All models outperform linear theory

Abstract

We have continued the development of Lagrangian, cosmological perturbation theory for the low-order correlators of the matter density field. We provide a new route to understanding how the effective field theory (EFT) of large-scale structure can be formulated in the Lagrandian framework and a new resummation scheme, comparing our results to earlier work and to a series of high-resolution N-body simulations in both Fourier and configuration space. The `new' terms arising from EFT serve to tame the dependence of perturbation theory on small-scale physics and improve agreement with simulations (though with an additional free parameter). We find that all of our models fare well on scales larger than about two to three times the non-linear scale, but fail as the non-linear scale is approached. This is slightly less reach than has been seen previously. At low redshift the Lagrangian model fares as well as EFT in its Eulerian formulation, but at higher $z$ the Eulerian EFT fits the data to smaller scales than resummed, Lagrangian EFT. All the perturbative models fare better than linear theory.