Effective Generalized Hubbard Model with QUantum Symmetry

Arianna Montorsi, Mario Rasetti

E. Ahmed, Ahmed Sadek Hegazi

Giuseppe Albertini, V. E. Korepin, Andreas Schadschneider

We consider the limit of strong Coulomb attraction for generalized Hubbard models with eta -symmetry. In this limit these models are equivalent to the ferromagnetic spin- 1/2 Heisenberg quantum spin chain. In order to study the behaviour of the superconducting phase in the electronic model under perturbations which break the eta -symmetry we investigate the ground state of the ferromagnetic non-critical XXZ-chain in the sector with fixed magnetization. It turns out to be a large bound state of N magnons. We find that the perturbations considered here lead to the disappearance of the off-diagonal long-range order.

E. Ahmed, A. S. Hegazi

Harald Grosse

Peter Schupp

We discuss classical and quantum symmetries of extended Hubbard models. The quantum symmetries are shown to be related to the known superconducting SU(2) symmetry of the original Hubbard model at half filling via generalized Lang-Firsov transformations and Drinfel'd twists. (Based on talk at the 21st ICGTM in Goslar, July 1996)