The existence of a quantum phase transition in a Hubbard model on a square lattice
arXiv:1404.3140
Abstract
A novel canonical transformation is offered as the mean for studying properties of a system of strongly correlated electrons. As an example of the utility of the transformation, it is used to demonstrate the existence of a quantum phase transition in a Hubbard model on a square lattice. An Appendix presents two cases with a negative result.
7 pages (with an added appendix)