Remarks and generalizations about SU2×SU2 symmetry of Hubbard models

Arianna Montorsi, Mario Rasetti

Elisa Ercolessi, G. Morandi, F. Ortolani

A remarkable global SO(4) symmetry of the Hubbard model, when there is on the average one electron per site (“weak” half-filling condition) has been recently uncovered by Yang and Zhang. We discuss here its relationship to the SU(2) gauge symmetry of the model that holds when there is exactly one electron per site (“strong” half-filling condition) as well as its possible generalizations to lattice structures more general than those considered by Yang and Zhang.

Ernst Nowak

Anilesh Mohari

In this paper, we have proved that there exists no translation invariant pure state of M=⊗k∈Z Md(k)(C) that is real, lattice symmetric with a certain twist and SU2(C) invariant for any even integer d ≥ 2. In particular, this result also shows that the Heisenberg iso-spin anti-ferromagnetic model with 12-odd integer spin degrees of freedom does not admit a unique ground state.

Denis B. Uglov, V. E. Korepin

E. Ahmed, A. S. Hegazi