Non-perturbative unitarity and fictitious ghosts in quantum gravity
Alessia Platania, C. Wetterich
Abstract
We discuss aspects of non-perturbative unitarity in quantum field theory. The additional ghost degrees of freedom arising in “truncations” of an effective action at a finite order in derivatives could be fictitious degrees of freedom. Their contributions to the fully-dressed propagator – the residues of the corresponding ghost-like poles – vanish once all operators compatible with the symmetry of the theory are included in the effective action. These “fake ghosts” do not indicate a violation of unitarity.
Topics & Concepts
UnitarityPropagatorPhysicsDegrees of freedom (physics and chemistry)Action (physics)Quantum field theoryQuantum gravityTheoretical physicsQuantumEffective actionField (mathematics)Classical mechanicsMathematical physicsQuantum mechanicsMathematicsPure mathematicsBlack Holes and Theoretical PhysicsNoncommutative and Quantum Gravity TheoriesCosmology and Gravitation Theories