Decomposition of the coherence relation in C*-algebraic many body physics

In quantum optics it is well known that interference effects of coherent light scattering do not depend on a monochromatic pure state preparation. A similar generalization of coherence is especially desirable in many body physics where the scattering of local perturbations and quasi-particle excitations of global equilibrium states are investigated, and where it is known that these are never pure states for finite temperatures. (Auth.)