The Interaction of Quantum Gravity with Matter

TL;DR

This paper investigates how linearized quantum gravity interacts with matter fields using a causal perturbation approach, demonstrating the universality of gravity's interaction without imposing new constraints on matter Lagrangians.

Contribution

It proves the universality of gravitational interaction with matter fields in a second-order perturbative framework using quantum off-shell fields.

Findings

Gravity interacts universally with matter fields.

No new constraints on matter Lagrangians from gravitational interaction.

Simplified computation via quantum off-shell formalism.

Abstract

The interaction of (linearized) gravitation with matter is studied in the causal approach up to the second order of perturbation theory. We consider the generic case and prove that gravitation is universal in the sense that the existence of the interaction with gravitation does not put new constraints on the Lagrangian for lower spin fields. We use the formalism of quantum off-shell fields which makes our computation more straightforward and simpler.