# Physics at the LHC and beyond

29 September 2015 to 2 October 2015
DESY Hamburg
Europe/Berlin timezone

## On the Soft Limit of the Large Scale Structure Power Spectrum: UV Dependence

1 Oct 2015, 16:50
15m
Seminar room 2 (DESY Hamburg)

### Speaker

Laura Sagunski (DESY Hamburg)

### Description

We derive a non-perturbative equation for the large scale structure power spectrum of long-wavelength modes. We use an operator product expansion together with relations between the three-point function and power spectrum in the soft limit. The resulting equation encodes the coupling to ultraviolet (UV) modes in two time-dependent coefficients, which may be obtained from response functions to (anisotropic) parameters, such as spatial curvature, in a modified cosmology. We argue that both depend weakly on fluctuations deep in the UV. As a byproduct, this implies that the renormalized leading order coefficient(s) in the effective field theory (EFT) of large scale structures receive most of their contribution from modes close to the non-linear scale. Consequently, the UV dependence found in explicit computations within standard perturbation theory stems mostly from counter-term(s). We confront a simplified version of our non-perturbative equation against existent numerical simulations, and find good agreement within the expected uncertainties. Our approach can in principle be used to precisely infer the relevance of the leading order EFT coefficient(s) using small volume simulations in an `anisotropic separate universe' framework. Our results suggest that the importance of these coefficient(s) is a $\sim 10 \%$ effect, and plausibly smaller.

### Primary authors

Laura Sagunski (DESY Hamburg) Mathias Garny (CERN Theory Division) Rafael A. Porto (ICTP South American Institute for Fundamental Research, Sao Paulo, Brazil) Thomas Konstandin (DESY Hamburg)

 Slides