Recently it was established that a certain integrable long-range spin chain describes the dilatation operator of N = 4 gauge theory in the su(2) sector to at least three-loop order, while exhibiting BMN scaling to all orders in perturbation theory. Here we identify this spin chain as an approximation to an integrable short-rangedmodel of strongly correlated electrons: The Hubbard model.

We study stripes in cuprates within the one-band and the three-band Hubbard model. Magnetic and charge excitations are described within the time-dependent Gutzwiller approximation. A variety of experiments (charge profile from resonant soft X-ray scattering, incommensurability vs. doping, optical excitations, magnetic excitations, etc.) are described within the same approach.

A strong-coupling expansion for the antiferromagnetic phase of the Hubbard model is derived in the framework of the slave-boson mean-field approximation. The expansion can be obtained in terms of moments of the density of states of freely hopping electrons on a lattice, which in turn are obtained for hypercubic lattices in arbitrary dimension. The expansion is given for the case of half-filling...

As is generally known, the polaron concept was introduced by Landau in 1933 [1]. Gradually a distinction was made between polarons in the continuum approximation where long-range electron-lattice interaction prevails (“Fröhlich”polarons) and polarons for which the short-range interaction is essential (Holstein, Holstein-Hubbard models). After a period of initial theoretical [1, 2, 3, 4, 5, 6, 7...

We employ the dynamical cluster approximation ~DCA! in conjunction with the fluctuation exchange approximation ~FLEX! to study the Hubbard model. The DCA is a technique to systematically restore the momentum conservation at the internal vertices of Feynman diagrams relinquished in the dynamical mean field approximation. The FLEX is a perturbative diagrammatic approach in which classes of Feynma...