Non-Fermi liquid behavior in an extended Anderson model
  An extended Anderson model, including screening channels (non-hybridizing, but interacting with the local orbit), is studied within the Anderson-Yuval approach, originally devised for the single-channel Kondo problem. By comparing the perturbation expansions of this model and a generalized resonant level model, the spin-spin correlation functions are calculated which show non-Fermi liquid exponent depending on the strength of the scattering potential. The relevance of this result to experiments in some heavy fermion systems is briefly discussed. 
Yu-Liang Liu, Zhao-Bin Su, and Lu Yu (ICTP, Trieste, Italy and ITP,   CAS, Beijing, China)