Emery-Kivelson line and universality of Wilson ratio of spin anisotropic Kondo model

Yuval-Anderson scaling analysis and Affleck-Ludwig conformal field theory approach are applied to the k channel spin anisotropic Kondo model. Detailed comparisons with the available Emery-Kivelson (EK) Abelian bosonization approaches are made. It is shown that the EK line exists for any Ic, although it can be mapped to free fermions only when k = 1 or 2. The Wilson ratio is universal if k = 1 or 2, but nut universal if k > 2. The leading low temperature correction to the electron resistivity is not affected by the spin anisotropy fur any k. A new universal ratio for k > 2 is proposed to compare with experiments.