The Problem of Classical Limit in Quantum Cosmology: The effective action language

TL;DR

This paper explores how the effective action approach reveals a quantum 'repel' phenomenon in constrained quantum cosmological systems, highlighting the impact of constraints on classical limits.

Contribution

It introduces a novel application of the effective action framework to quantum cosmology, demonstrating the quantum 'repel' effect due to constraints.

Findings

Constraints induce a quantum 'repel' from the classical mass shell.

Toy models illustrate the generality of the phenomenon.

Effective action language clarifies quantum effects in constrained systems.

Abstract

The tool of functional averaging over some ``large'' diffeomorphisms is used to describe quantum systems with constraints, in particular quantum cosmology, in the language of quantum Effective Action. Simple toy models demonstrate a supposedly general phenomenon: the presence of a constraint results in ``quantum repel'' from the classical mass shell.