Snowmass White Paper: Effective Field Theories in Cosmology

TL;DR

This paper reviews how effective field theories serve as a unifying framework to understand the origin and evolution of cosmological fluctuations during inflation, large-scale structure formation, and dark energy, linking fundamental parameters to observations.

Contribution

It provides a comprehensive summary of the application of effective field theories in cosmology, highlighting their role in unifying various models and connecting theory with observations.

Findings

Effective field theories unify diverse cosmological models.

They connect fundamental parameters with observable data.

The framework applies to inflation, structure formation, and dark energy.

Abstract

Small fluctuations around homogeneous and isotropic expanding backgrounds are the main object of study in cosmology. Their origin and evolution is sensitive to the physical processes that happen during inflation and in the late Universe. As such, they hold the key to answering many of the major open questions in cosmology. Given a large separation of relevant scales in many examples of interest, the most natural description of these fluctuations is formulated in terms of effective field theories. This was the main avenue for many of the important modern developments in theoretical cosmology, which provided a unifying framework for a plethora of cosmological models and made a clear connection between the fundamental cosmological parameters and observables. In this review we summarize these results in the context of effective field theories of inflation, large-scale structure, and dark energy.