Exact solution of the s-d exchange model (Kondo problem)

It is shown that the s-d exchange model (the Kondo problem) is a completely integrable one and that the Bethe hypothesis is valid for it. The equilibrium properties of a magnetic impurity in a metal at T=0 are described in terms of the Wiener-Hopf integral equation. The explicit formula for the magnetic susceptibility as a function of the magnetic field is derived. The solution of the Kondo problem with anisotropic exchange in the region J/sub ///> mod J perpendicular to mod is presented too. The author concludes by a brief section in which it is shown that the Anderson model is also completely integrable.