STRONG-COUPLING REGIME IN THE 2-DIMENSIONAL HUBBARD-MODEL

The physical properties of two-dimensional interacting electron system s are of great current interest. An open question in the physics of lo w-dimensional Fermionic models is whether their properties are describ ed by standard Fermi liquid theory or whether instead they show unconv entional behaviour in strongly correlated electron systems. As the two -dimensional Hubbard model is the typical example of a strongly correl ated electron system, we solve for this model and its extended t-t'-U model, the two-body problem of two electrons in the vicinity of a half -filled Fermi sea. The obtained results show that for small hole conce ntration none of these models follow the well-known Fermi liquid pictu re. (C) 1998 Elsevier Science B.V. All rights reserved.