Coherence scale of the two-dimensional Kondo Lattice model
  A doped hole in the two-dimensional half-filled Kondo lattice model with exchange J and hopping t has momentum (pi,pi) irrespective of the coupling J/t. The quasiparticle residue of the doped hole, Z_{(\pi, \pi)}, tracks the Kondo scale, T_K, of the corresponding single impurity model. Those results stem from high precision quantum Monte Carlo simulations on lattices up to 12 X 12. Accounting for small dopings away from half-filling within a rigid band approximation, this result implies that the effective mass of the charge carriers at the Fermi level tracks 1/T_K or equivalently that the coherence temperature T_{coh} \propto T_K. This results is consistent with the large-N saddle point of the SU(N) symmetric Kondo lattice model. 
F.F. Assaad