Non-particle statistical physics
  Consistent statistical physical description is given for systems where the elementary excitations are composite objects. Explicit calculational scheme is constructed for the energy density and the total number of thermodynamical degrees of freedom, based on the spectral function of the system. One demonstrates through characteristic examples that single quasiparticle contributions combine non-linearly in these quantities. Relation to the Gibbs paradox is also discussed. 
A. Jakovac
hep-ph cond-mat.stat-mech hep-th