A Field Theory for Quantum Markov Processes

Masao Nagasawa

Bassano Vacchini

V.G. Kadyshevskij

Detlef Dürr, Sheldon Goldstein, Roderich Tumulka +1 more

In his paper (1986 Beables for quantum field theory Phys. Rep. 137 49–54) John S Bell proposed how to associate particle trajectories with a lattice quantum field theory, yielding what can be regarded as a |Ψ| 2 -distributed Markov process on the appropriate configuration space. A similar process can be defined in the continuum, for more or less any regularized quantum field theory; we call such processes Bell-type quantum field theories. We describe methods for explicitly constructing these processes. These concern, in addition to the definition of the Markov processes, the efficient calculation of jump rates, how to obtain the process from the processes corresponding to the free and interaction Hamiltonian alone, and how to obtain the free process from the free Hamiltonian or, alternatively, from the one-particle process by a construction analogous to ‘second quantization’. As an example, we consider the process for a second quantized Dirac field in an external electromagnetic field.

Carlo Cecchini

Franesco Guerra, Patrizia Ruggiero

The Euclidean-Markov field, extensively used in constructive quantum field theory, is shown to be the same as the lowest energy generalized stochastic process associated with classical field theory through the procedure of Nelson's stochastic mechanics. As a result, the underlying four-dimensional manifold, on which the Markov field is defined, can be considered as the physical space-time.