THE EXACT RENORMALIZATION GROUP AND PAIRING IN MANY-FERMION SYSTEMS

Khandker Quader, Renyuan Liao

Khandker Quader

K. A. Penson, M. Kolb

B. Alascio, Eduardo R. Gagliano, M. Avignon +1 more

We model the Cu-O high T c compounds by a generalized Hubbard Hamiltonian that includes an intersite Coulomb repulsion G. We use a real space renormalization group approach to calculate effective interactions and gap energies in infinite chains. The results indicate attraction between added holes in these systems. The magnitudes of these attractive energies are compared with exact results obtained by the Lanczos method for finite clusters.

Boris Krippa, Michael C. Birse, Niels R. Walet +1 more

Boris Krippa, Michael C. Birse, Judith A. McGovern +1 more

The exact renormalization group method is applied to many-fermion systems with short-range attractive forces. The strength of the attractive fermion-fermion interaction is determined from the vacuum scattering length. A set of approximate flow equations is derived including fermionic bosonic fluctations. The numerical solutions show a phase transition to a gapped phase. The inclusion of bosonic fluctuations is found to be significant only in the small-gap regime.