Toda solitons as Fermi-quasiparticles

The Bethe ansatz leads to Yang-Yang integral equations. The particle-hole structure of the zero-temperature excitations is generalized to finite temperatures, which leads to the definition of soliton- and phonon-quasiparticles. The solitons approximately follow the Fermi-Dirac statistics and have a chemical potential with an unusual temperature dependence, because the number of solitons is not constant.