# The Fr\"ohlich-Morchio-Strocchi mechanism and quantum gravity

## TL;DR

This paper explores how gauge and diffeomorphism invariance guide the construction of physical objects in quantum gravity, revealing that quantum fields require dressing with gravitons to form observable particles, and clarifies the physical spectrum of gravitational degrees of freedom.

## Contribution

It applies the Fröhlich-Morchio-Strocchi mechanism to quantum gravity, showing how physical objects are classified and how quantum gravity fields dress quantum fields to produce observable particles.

## Key findings

- Physical objects are classified by tangent space quantum numbers.
- Quantum fluctuations of gravity diminish, objects align with standard quantum-field theory.
- Quantum gravity fields dress quantum fields, incorporating gravitons into particles.

## Abstract

Taking manifest invariance under both gauge symmetry and diffeomorphisms as a guiding principle physical objects are constructed for Yang-Mills-Higgs theory coupled to quantum gravity. These objects are entirely classified by quantum numbers defined in the tangent space. Applying the Fr\"ohlich-Morchio-Strocchi mechanism to these objects reveals that they coincide with ordinary correlation functions in quantum-field theory, if quantum fluctuations of gravity and curvature become small. Taking these descriptions literally exhibits how quantum gravity fields need to dress quantum fields to create physical objects, i.e. giving a graviton component to ordinary observed particles. The same mechanism provides access to the physical spectrum of pure gravitational degrees of freedom.