Bethe-ansatz approach to the Kondo model with arbitrary impurity spin

The Kondo model with a spin-S impurity is formulated using a generalization of the Bethe-Yang approach. The exact relation between high- and low-temperature dimensional scales is obtained for arbitrary S The formalism is further generalized to include two species of electrons. It is found, contrary to expectations, that the screening of the impurity's magnetic moment is not dependent on the number of species: The spin of the dressed impurity is S-1/2 in both cases. To ensure that no states have been overlooked the completeness of the basis is examined in some detail.