The effects of the propagation of particles which have a finite life-time and an according width in their mass spectrum are discussed in the context of transport descriptions. In the first part general properties of broad resonances in dense matter and at finite temperature are discussed. First self consistent calculations of the interacting pion-rho-meson system at finit temperatures are presented, treating all propagators with finite damping width within an effective action approach, truncated to the level of two-point functions.

The second part addresses the problem of a quantum transport descriptions which dynamically account for the differential spectral information contained in the spectral functions of the particles. The Kadanoff-Baym equation after gradient approximation together with the Phi-derivable method of Baym provides a self-consistent and conserving scheme, suitable to describe the dynamics of broad structures. For the Phi-derivable approximation the energy momentum tensor is constructed explicitly. The validity conditions of the gradient approximation are given. Various forms of the collision term including memory effects appearing in phi-diagrams of higher order are discussed. We further derive a generalized expression for the non-equilibrium kinetic entropy flow, which includes corrections from fluctuations and damping-width effects. In special cases an H-theorem is proved. Memory effects in collision terms provide contributions to the kinetic entropy flow that in the Fermi-liquid case recover the famous bosonic type T^3 ln (T) correction to the specific heat of liquid Helium-3.

For further details see