An Analytical Strong Coupling Approach in Dynamical Mean-Field Theory

In the limit of infinite spatial dimensions a thermodynamically consistent theory of the strongly correlated electron systems, which is valid for arbitrary value of the Coulombic interaction (U<∞ ), is built. For the Hubbard model the total auxiliary single-site problem exactly splits into four subspaces, which describe Fermi and non-Fermi liquid components. Such analytical approach allows to construct different thermodynamically consistent approximations: alloy-analogy approximation, Hartree--Fock approximation, and further, that which describes the self-consistent renormalization of the bosonic excitations (magnons and doublons).