Thermodynamics of the anisotropic two-channel Kondo problem

We construct and solve numerically the thermodynamic Bethe-ansatz equations for the spin-anisotropic two-channel Kondo model in arbitrary external field h. At high temperatures the specific heat and the susceptibility show power-law dependence. For →h0 and at temperatures below the Kondo temperature TK a two-channel Kondo effect develops characterized by a Wilson ratio $8/3,$ and a logarithmic divergence of the susceptibility and the linear specific-heat coefficient. A finite magnetic field, $h>0,$ drives the system to a Fermi-liquid fixed point with an unusual Wilson ratio which depends sensitively on h.