We study the non-Fermi liquid behavior in a two-band extended Hubbard model. In the limit of infinite dimensions, where only local correlations are taken into account, this model in the mixed-valence regime is known to display a metallic non-Fermi liquid phase with spin-charge separation. Here we address the effect of intersite RKKY-like interactions using an extended dynamical mean-field approach. We find that the spin-charge separation survives the quantum fluctuations associated with the intersite density-density and spin-exchange interactions. We determine the spin, charge, and single-particle correlation functions in the non-Fermi liquid state.
I summarize recent work on non-Fermi liquids within a certain generalized Anderson impurity model as well as in the large-dimensionality (D) limit of the two-band extended Hubbard model. The competition between local charge and spin fluctuations leads either to a Fermi liquid with renormalized quasiparticle excitations, or to non-Fermi liquids with spin - charge separation. These results provide new insights into the phenomenological similarities and differences between different correlated metals. While presenting these results, I outline a general strategy of local approach to non-Fermi liquids in correlated electron systems.