# Effective Field Theory of Loop Quantum Cosmology

## TL;DR

This paper develops an effective field theory approach to loop quantum cosmology, highlighting how infrared renormalization impacts quantum corrections and the treatment of inhomogeneities in cosmological models.

## Contribution

It introduces an effective field theory framework for loop quantum cosmology that incorporates infrared renormalization effects, addressing limitations of minisuperspace models.

## Key findings

- Infrared scale is identified with the inhomogeneous modes' IR cutoff.
- Renormalization affects quantum corrections in cosmological models.
- Homogeneity regions shrink during gravitational collapse due to IR effects.

## Abstract

Quantum cosmology is traditionally formulated in a minisuperspace setting, implicitly averaging fields over space to obtain homogeneous models. For universal reasons related to the uncertainty principle, quantum corrections then depend on the size of the averaging volume. In minisuperspace truncations, the value of this volume remains an arbitrary parameter devoid of physical meaning, but in an effective field theory it is identified with the infrared scale of inhomogeneous modes. Moreover, the infrared scale is running during gravitational collapse, when regions in which homogeneity remains approximately valid shrink to increasingly smaller co-moving sizes. Conceptual implications of this infrared renormalization for perturbative inhomogeneity in quantum cosmology are presented here, mainly for the example of loop quantum cosmology. Several claims made in this framework are altered by infrared renormalization.