Physics (Internal)

Soft-pion theorems and the nonlinear regime of large scale structure

This event is part of the HET Seminar Series.

Abstract: Consistency relations, which relate the squeezed limit of an N+1-point function to an N-point function, are extremely useful nonperturbative symmetry statements in cosmology and remain valid even when the N-point function is deep in the nonlinear regime. In this talk I will discuss the derivation of these relations in conformal Newtonian gauge, with velocity potential playing the role of the soft pion, their robustness under astrophysical complications, and the connection to previously derived relations in zeta (unitary) gauge. The simplest of these consistency relations has an especially simple expression in Lagrangian coordinates, which suggests that an analytic understanding of large scale in the nonlinear regime may be particularly promising in this picture.