Interaction Theory

Marcel Theodorus Maria van Kessel

We show how one can reproduce the state evolution known from interacting QFT from an ontological deterministic theory. This is an important step in finding the reality that underlies QFT.In previous work ontic theories behind free QFTs were found, for all QFTs that occur in the Standard Model (spin-0, spin-1/2 & spin-1). In this paper we extend the ontological theory behind QFT to the case with interactions. We do this by starting out from the ontic theories found for free QFTs and see what happens if we try to include interactions (known from QFT). This will lead us to the conjecture that the ontic theory behind any QFT with interaction is, at the basis, the corresponding classical field theory. We study such a classical field theory for the case of a real scalar field with φn-interaction. We determine the evolution of the probability density of the ontic fields and cast it into a formalism known from QFT. We will focus on the simplest case of self-interaction, to illustrate our procedure. We find that we can reproduce the probability evolution from real scalar QFT with (self-)interaction, for this simplest case.

Ian T. Durham, Dean P. Rickles

Giuseppe Nisticò

We point out a difficulty that arises in extending the group theoretical approach that deductively establish the quantum theory of a free particle to the case of an interacting particle. Then we develop an approach which overcomes this difficulty. The result is a theory of an interacting particle where the standard theory is characterized by specific covariance properties related to the interaction.

Hermann Grabert

Arne Hansen, Wolf, Stefan

Results of measurements give legitimacy to a physical theory. What if acquiring these results in the first place necessitates what the same theory considers to be an interaction? In this note, we assume that theories account for interactions so that they are empirically traceable, and that observations necessarily go with such an interaction with the observed system. We investigate consequences of this assumption: The unfolding language game, inspired by "quantum logic," leads to a class of contextual and probabilistic theories. Contextuality becomes a means to render interactions, thus also measurements, empirically tangible. The measurement "problem" arises in all such theories, not only quantum mechanics: It is a consequence of the need for empirical evidence of interactions. And a consequence of the converse need for an interaction when obtaining that empirical evidence.

John C. Inkson