Spin-flavor separation and non-Fermi-liquid behavior in the multichannel Kondo problem: A large-N approach.

We present an analytical solution of a SU(N)\ifmmode\times\else\texttimes\fi{}SU(M) generalization of the multichannel single-impurity Kondo model in the limit N\ensuremath{\rightarrow}\ensuremath{\infty}, M\ensuremath{\rightarrow}\ensuremath{\infty}, with \ensuremath{\gamma}=M/N fixed. Non-Fermi-liquid behavior of the single electron Green function and of the local spin and flavor susceptibilities occurs in both regimes, N\ensuremath{\le}M and NgM, with leading critical exponents identical to those found in the conformal field theory solution for all N and M (with M\ensuremath{\ge}2). We explain this remarkable agreement and connect it to ``spin-flavor separation,'' the essential feature of the non-Fermi-liquid, fixed point.