Quantum fields, cosmological constant and symmetry doubling
  Energy-parity has been introduced by Kaplan and Sundrum as a protective symmetry that suppresses matter contributions to the cosmological constant [KS05]. It is shown here that this symmetry, schematically Energy --> - Energy, arises in the Hilbert space representation of the classical phase space dynamics of matter. Consistently with energy-parity and gauge symmetry, we generalize the Liouville operator and allow a varying gauge coupling, as in "varying alpha" or dilaton models. In this model, classical matter fields can dynamically turn into quantum fields (Schroedinger picture), accompanied by a gauge symmetry change -- presently, U(1) --> U(1) x U(1). The transition between classical ensemble theory and quantum field theory is governed by the varying coupling, in terms of a one-parameter deformation of either limit. These corrections introduce diffusion and dissipation, leading to decoherence. 
Hans-Thomas Elze