U(1) slave-particle study of the finite-temperature doped Hubbard model in one and two dimensions

One-dimensional systems have unusual properties such as fractionalization of degrees of freedom. The occurrence of similar phenomena in higher dimensional systems has been considered in the literature for the description of quantum spin liquids and some non-fermi liquid phases. In this work we construct a mean field (MF) theory of the Hubbard model which is based on a representation of the electronic fields that explicitly introduces a separation of the charge and spin degrees of freedom (the so-called Zou–Anderson transformation) and study the finite-temperature phase diagram for the Hubbard chain and square lattice. The mean field variables are defined along the links of the underlying lattice. We obtain the spectral function and identify the regions of higher spectral weight with the fractionalized fermionic (spin) and bosonic (charge) excitations.