Topological nature of Hubbard bands in strongly correlated systems

The topological nature of the Mott-Hubbard state in strongly correlated systems is treated. These systems are described in terms of spin-charge separation, i.e. spinon-holon deconfinement in the gauge field. Analogies with the quantum Hall effect and Landau quantization are considered, the presence of the Chern-Simons term being important for proper description of the Hubbard splitting. Occurrence of topological frustrations with doping in an effective two-band model is demonstrated. The role of orbital degrees of freedom and possible occurrence of orbital currents are discussed.