2-BODY AND 3-BODY CORRELATION IN DILUTE HUBBARD SYSTEMS

In order to find an exact solution for the Hubbard systems with few el ectrons, we have developed a new method, which consists of mapping the original many-body problem onto a tight-binding one in a higher-dimen sional space. Applying this mapping method to a chain, a square lattic e and a triangular one, the pairing problem of two electrons and two h oles with anti-parallel spins has been analyzed by looking at the bind ing energy and the coherence length for attractive interactions. Final ly, some results of the three-body correlation are also reported.