Two-Dimensional Solitons at Finite Temperature
  The partition function of two-dimensional solitons in a heat bath of mesons is worked out to one-loop. For temperatures large compared to the meson mass, the free energy is dominated by the meson-soliton bound states and the zero modes, a consequence of Levinson's theorem. Using the Bethe-Uhlenbeck formula we compare the soliton energy-shift to the shift expected in the pole mass using a virial expansion. We construct the partition function associated to a fast moving soliton at finite temperature, and found that the soliton thermal inertial mass is no longer constrained by Poincare's symmetry. At finite temperature, the concept of quasiparticles is process dependent. 
M. Kacir and I. Zahed