Remarks on Causality in Relativistic Quantum Field Theory

Remarks on Causality in Relativistic Quantum Field Theory

It is shown that the correlations predicted by relativistic quantum field theory in locally normal states between projections in local von Neumann algebras A(V1),A(V2) associated with spacelike separated spacetime regions V1, V2 have a (Reichenbachian) common cause located in the union of the backward light cones of V1 and V2. Further comments on causality and independence in quantum field theo...

Relativistic Quantum Field Theory

Remarks on twisted noncommutative quantum field theory

We review recent results on twisted noncommutative quantum field theory by embedding it into a general framework for the quantization of systems with a twisted symmetry. We discuss commutation relations in this setting and show that the twisted structure is so rigid that it is hard to derive any predictions, unless one gives up general principles of quantum theory. It is also shown that the twi...

Causality and Chance in Relativistic Quantum Field Theories

Bell appealed to the theory of relativity in formulating his principle of local causality. But he maintained that quantum …eld theories do not conform to that principle, even when their …eld equations are relativistically covariant and their observable algebras satisfy a relativistically motivated microcausality condition. A pragmatist view of quantum theory and an interventionist approach to c...

Quasiparticle excitations in relativistic quantum field theory

We analyze the particle-like excitations arising in relativistic field theories in states different than the vacuum. The basic properties characterizing the quasiparticle propagation are studied using two different complementary methods. First we introduce a frequency-based approach, wherein the quasiparticle properties are deduced from the spectral analysis of the twopoint propagators. Second,...