Effective quantum field theories in general spacetimes

TL;DR

This paper introduces regular charts as a universal way to define effective quantum field theories in any spacetime, enabling background-independent coupling to gravity without back-reaction effects.

Contribution

It proposes a novel framework using regular charts for defining effective QFTs in arbitrary spacetimes, including quantum gravity, independent of background metrics.

Findings

Effective QFTs can be defined in any spacetime using regular charts.

Coupling to classical gravity is possible without back-reaction effects.

The approach includes a method for effective QFTs with quantum gravity.

Abstract

We introduce regular charts as physical reference frames in spacetime, and we show that general spacetimes can always be fully captured by regular charts. Effective quantum field theories (QFTs) can be conveniently defined in regular reference frames, and the definition is independent of specific background metric and independent of specific regular reference frame. As a consequence, coupling to classical gravity is possible in effective QFTs without getting back-reaction effects. Moreover, we present an approach to effective QFTs including quantum gravity.