Ward Identity Constraints on Loop Corrections in Non-Attractor Inflation

TL;DR

This paper shows that symmetry principles, specifically Ward identities, impose strict constraints on loop corrections to curvature perturbations in non-attractor inflation, ensuring their conservation.

Contribution

It establishes a non-perturbative, symmetry-based framework linking Ward identities to the conservation of super-horizon perturbations in inflation.

Findings

Ward identities impose strict constraints on infrared power spectra.

Conservation of super-horizon curvature perturbations follows from symmetry.

Provides a rigorous framework for nonlinear quantum fluctuations in inflation.

Abstract

The conservation of super-horizon curvature perturbations in strongly interacting inflationary models, particularly in the presence of quantum-loop corrections, remains a topic of active debate. We found that this conservation is essentially a direct consequence of the symmetry in perturbation theory. We demonstrate that the associated Ward identity imposes strict non-perturbative constraints on the infrared power spectrum. This finding provides a rigorous, symmetry-based framework for understanding nonlinear quantum fluctuations in the primordial universe.