Theory HEP Seminar

The effective field theory approach to cosmological perturbation theory

Simon Foreman

CITA

The science return of ongoing and planned large galaxy surveys will be greatly enhanced if we can make robust predictions for the clustering of matter on weakly nonlinear cosmological scales. In this talk, I will describe a framework, known as the Effective Field Theory of Large-Scale Structure (EFTofLSS), that is able to provide such predictions as a controlled perturbative expansion around linear theory. Drawing inspiration from the EFT approach to low-energy particle physics, the EFTofLSS augments the standard fluid description of dark matter with an "effective" stress tensor that parametrizes the effects of small-scale physics on large-scale clustering. This leads to a systematic way to compute nonlinear corrections to observables (specifically, N-point function of density and velocity fields) relevant for cosmological observations, without the convergence issues that have plagued previous perturbative approaches. I will review the motivation for, and essential features of, the EFTofLSS, and present a collection of results that demonstrate the theory's ability to match the output of N-body simulations with high precision. I will conclude by previewing ongoing work related to new applications of the theory, as well as some initial steps towards uncovering hidden structures within the theory itself.