SCALING LIMIT OF THE ONE-DIMENSIONAL ATTRACTIVE HUBBARD-MODEL - THE HALF-FILLED BAND CASE

The scaling limit of the higher level Bethe Ansatz (HLBA) equations fo r a macroscopically half-filled Hubbard chain is considered, These equ ations practically decouple into three disjoint sets which are again o f the BA type, and correspond to the secular equations of three differ ent kinds of dressed particles (one massive and two massless). The fin ite size corrections and the fine structure of the spectrum show that the massless sector corresponds to a conformal field with central char ge c = 1 and Gaussian anomalous dimensions. The zero temperature free energy is also calculated and is found to be in perfect agreement with the results of a perturbative calculation in the SU(2) chiral Gross-N eveu (CGN) model. Some further arguments are presented supporting the identification of the model obtained as the relativistic limit of the half-filled Hubbard chain with the SU(2) CGN model. (C) 1997 Elsevier Science B.V.