Spin-Flavor Separation and Non-Fermi Liquid Behavior in the Multichannel Kondo Problem: A Large N Approach

TL;DR

This paper analytically solves a generalized multichannel Kondo model in the large N limit, revealing universal non-Fermi liquid behavior and spin-flavor separation across different regimes, consistent with conformal field theory results.

Contribution

It provides an exact large N solution of the multichannel Kondo model, demonstrating universal non-Fermi liquid behavior and connecting it to spin-flavor separation.

Findings

Non-Fermi liquid behavior in Green functions and susceptibilities.

Critical exponents match conformal field theory predictions.

Spin-flavor separation is key to the non-Fermi-liquid fixed point.

Abstract

We consider a $SU(N)\times SU(M)$ generalization of the multichannel single-impurity Kondo model which we solve analytically in the limit $N\rightarrow \infty$, $M\rightarrow\infty$, with $\gamma=M/N$ fixed. Non-Fermi liquid behavior of the single electron Green function and of the local spin and flavor susceptibilities occurs in both regimes, $N\le M$ and $N > M$, with leading critical exponents {\em identical} to those found in the conformal field theory solution for {\em all} $N$ and $M$ (with $M\ge 2$). We explain this remarkable agreement and connect it to ``spin-flavor separation", the essential feature of the non-Fermi-liquid fixed point of the multichannel Kondo problem.