ar X iv : c on d - m at / 9 50 11 19 v 1 2 5 Ja n 19 95 Spectral weight function for the half - filled Hubbard model : a singular value decomposition approach

Spectral weight function for the half-filled Hubbard model: A singular value decomposition approach.

The singular value decomposition technique is used to reconstruct the electronic spectral weight function for a half-filled Hubbard model with on-site repulsion U = 4t from quantum Monte Carlo data. A two-band structure for the single-particle excitation spectrum is found to persist as the lattice size exceeds the spin-spin correlation length. The observed bands are Hat in the vicinity of the (...

ar X iv : c on d - m at / 9 40 10 66 v 1 2 8 Ja n 19 94 Ground state energy and quasiparticle gaps

ar X iv : c on d - m at / 9 40 90 65 v 1 1 5 Se p 19 94 UCI - CMTHE - 94 - 05 The Doped Two Chain Hubbard Model

The properties of the two–chain Hubbard Model doped away from half–filling are investigated. The charge gap is found to vanish, but a finite spin gap exists over a range of interchain hopping strength t ⊥. In this range, there are modified d x 2 −y 2 –like pairing correlations whose strength is correlated with the size of the spin gap. It is found that the pair field correlations are enhanced b...

ar X iv : c on d - m at / 9 40 10 05 v 2 1 0 Ja n 19 94 Composite operators for BCS Superconductor

The new form of the composite operator generalizing the Cooper pairs for a BCS superconductor is introduced. The approach is similar to the derivation of the composite operator of the odd-frequency superconductors. The examples of the d x 2 −y 2 −, d xy − and p− wave composite operators for a 2D t − J model are given.

ar X iv : c on d - m at / 9 90 64 41 v 1 3 0 Ju n 19 99 FINITE TEMPERATURE TRANSPORT IN INTEGRABLE QUANTUM MANY BODY SYSTEMS

Recent developments in the analysis of finite temperature dissipationless transport in inte-grable quantum many body problems are presented. In particular, we will discuss: (i) the role played by the conservation laws in systems as the spin 1/2 Heisenberg chain and the one-dimensional Hubbard model, (ii) exact results obtained using the Bethe ansatz method on the long time decay of current corr...