Anomalies, equivalence and renormalization of cosmological frames

TL;DR

This paper investigates the impact of quantum anomalies on the equivalence of different cosmological frames, specifically Einstein and Jordan frames, showing that quantum corrections can break their classical equivalence.

Contribution

It demonstrates that quantum anomalies can cause inequivalence between cosmological frames, affecting their physical interpretation and requiring different UV completions.

Findings

Quantum anomalies break frame equivalence in scalar-tensor theories.

Renormalized theories develop frame-dependent contributions to the S-matrix.

Different frames may represent distinct physical theories needing separate UV completions.

Abstract

We study the question of whether two frames of a given physical theory are equivalent or not in the presence of quantum corrections. By using field theory arguments we claim that equivalence is broken in the presence of anomalous symmetries in one of the frames. This is particularized to the case of the relation between the Einstein and Jordan frames in scalar-tensor theories used to describe early Universe dynamics. Although in this case a regularization that cancels the anomaly exists, the renormalized theory always develop a non-vanishing contribution to the S-matrix that is present only in the Jordan frame, promoting the different frames to different physical theories that must be UV completed in a different way.