Bethe-Salpeter eigenvalues and amplitudes for the half-filled two-dimensional Hubbard model

Abstract

Monte Carlo simulations are used to determine the eigenvalues and eigenfunctions of the particle-hole and particle-particle Bethe-Salpeter equations for 8×8 half-filled Hubbard lattice with U/t=4 and U/t=8. In the particle-hole channel, the dominant eigenvalue corresponds to the Q=(π,π) antiferromagnetic correlations. In the particle-particle channel the amplitude of the leading low-temperature eigenvalue is an even-frequency ${\mathit{d}}_{\mathit{x}}^2$-${\mathit{y}}^2$ singlet. Odd-frequency p-wave-singlet and s-wave-triplet amplitudes are also found.