Approximation of the theory by a decohered quantum-sector limit

Ascertain whether the sector of classical–quantum dynamics that effectively describes a fully quantum theory with a decohered spacetime subsystem provides a sufficiently accurate approximation to the classical–quantum gravity theory developed in this work.

Background

The classical–quantum framework can arise as an effective limit of a fully quantum theory in which one subsystem (spacetime) has decohered. If this limit well-approximates the present classical–quantum theory, it would help connect the proposal to fully quantum gravity frameworks.

The authors explicitly flag uncertainty about the quantitative adequacy of this approximation for the theory they paper here.