Emery-Kivelson solution of the two-channel Kondo problem

We consider the two-channel Kondo model in the Emery-Kivelson approach, and calculate the total susceptibility enhancement due to the impurity χᵢₘₚ={χ}-χbulk. We find that χᵢₘₚ exactly vanishes at the solvable point, in a completely analogous way to the singular part of the specific heat Cᵢₘₚ. A perturbative calculation around the solvable point yields the generic behavior χᵢₘₚ{~}log(1/T), Cᵢₘₚ{~}T logT and the known universal value of the Wilson ratio RW=8/3. From this calculation, the Kondo temperature can be identified and is found to behave as the inverse square of the perturbation parameter. The small-field, zero-temperature behavior χᵢₘₚ{~}log(1/h) is also recovered.