Derivation of the Interacting Boson Model from mean-field theory

Yongjun Liu, Jinming Dong, Chang-De Gong

The RVB model is investigated by a mean field theory, in which the holon is expressed by a fermion operator, and the spinon by a boson operator. The effective holon-holon interaction by exchanging the spinons is derived for . It is found that the interaction is attractive.

Olaf Scholten

Martin R. Zirnbauer, D.M. Brink

Krzysztof Byczuk, D. Vollhardt

Abstract We derive a dynamical mean‐field theory for mixtures of interacting bosons and fermions on a lattice (BF‐DMFT). The BF‐DMFT is a comprehensive, thermodynamically consistent framework for the theoretical investigation of Bose‐Fermi mixtures and is applicable for arbitrary values of the coupling parameters and temperatures. It becomes exact in the limit of high spatial dimensions d or coordination number Z of the lattice. In particular, the BF‐DMFT treats normal and condensed bosons on equal footing and thus includes the effects caused by their dynamic coupling. Using the BF‐DMFT we investigate two different interaction models of correlated lattice bosons and fermions, one where all particles are spinless (model I) and one where fermions carry a spin one‐half (model II). In model I the local, repulsive interaction between bosons and fermions can give rise to an attractive effective interaction between the bosons. In model II it can also lead to an attraction between the fermions.

Tai Kai Ng

In this paper we generalize slave-boson mean-field theory for $t\ensuremath{-}J$ model to the time-dependent regime, and derive transport equations for $t\ensuremath{-}J$ model, both in the normal and superconducting states. By eliminating the boson and constraint fields exactly at zero temperature in the linear-response regime we obtain a set of transport equations for physical electrons which have the same form as Landau transport equations for normal Fermi liquid and Fermi-liquid superconductor, respectively, with all Landau parameters explicitly given. Our theory can be viewed as a refined version of U(1) Gauge theory where all lattice effects are retained and strong correlation effects are reflected as strong Fermi-liquid interactions in the transport equation. Some experimental consequences are discussed.

E. Nadzhakov, I.N. Mikhailov