SOLUTION OF THE 2-IMPURITY, 2-CHANNEL KONDO MODEL

We solve the two-impurity, two-channel Kondo model using a combination of conformal invariance and bosonization techniques. In the odd-even symmetric case, the RKKY interaction is exactly marginal, resulting in a line of non-Fermi-liquid fixed points. Explicit formulas are given for the critical exponents and for the finite-size spectrum, which depend continuously on a single parameter. The marginal line spans a range of values of the RKKY coupling I which goes from the infinitely strong ferromagnetic point I=+ to a finite antiferromagnetic critical value Imin<0 beyond which a Fermi liquid is recovered. When the odd-even symmetry is broken, the marginal line is unstable for ferromagnetic I, while for antiferromagnetic I it extends into a manifold of fixed points. © 1995 The American Physical Society.