Key points are not available for this paper at this time.
We discuss the necessary modifications of the state space for quantum fields interacting with strong stationary external fields. In addition to the introduction of an indefinite metric, we discuss the possibility of having a positive-definite metric without a vacuum state.
Schroer et al. (Tue,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: