Equivalence between fractional exclusion statistics and Fermi liquid theory in interacting particle systems

We explore the connections between the description of interacting particles systems in terms of fractional exclusion statistics (FES) and other many-body methods used for the same purpose. We consider a system of particles with generic, particle-particle interaction in the quasi-classical limit and in the mean-field approximation. We define the FES quasiparticle energies, we calculate the FES parameters of the system and we deduce the equations for the equilibrium particle populations. The FES gas is "ideal", in the sense that the quasiparticle energies do not depend on the other quasiparticle levels populations and the sum of the quasiparticle energies is equal to the total energy of the system. We prove that this FES formalism is equivalent to the semi-classical or Thomas Fermi (TF) limit of the self-consistent mean-field theory and the FES quasiparticle populations may be calculated from the Landau quasiparticle populations by making the correspondence between the FES and the Landau quasiparticle energies. The FES provides a natural semi-classical ideal gas description of the interacting particle gas in a generic external potential and in any number of dimensions.