Particle-like property of vacuum states

The wave-particle duality of the vacuum states of quantum fields is considered and the particle-like property of the vacuum state of a quantum field is proposed as a vacuum-particle which carries the vacuum-energy and the vacuum-momentum of this field. The vacuum-particles can be introduced into the quantum field theory (QFT) naturally without disturbing its mathematical structures and calculation results, but makes the QFT more self-consistent. For instance, the interactions between charged particles and vacuum state of electromagnetic field appears automatically in the Feynman diagrams of the quantum electrodynamics (QED), with which the atomic spontaneous emission and the Casimir effect of quantum optics can be interpreted directly by the QED perturbation theory. Besides, the relation between vacuum-particles and spontaneous symmetry breaking is also discussed.