Low-energy excitations of the one-dimensional half-filled SU(4) Hubbard model with an attractive on-site interaction: Density-matrix renormalization-group calculations and perturbation theory

TL;DR

This paper studies the low-energy excitations of a one-dimensional SU(4) Hubbard model with attractive interactions, revealing a charge density wave ground state and analyzing excitation gaps through DMRG and perturbation theory.

Contribution

It combines density-matrix renormalization group calculations with perturbation theory to analyze the excitation spectrum of the SU(4) Hubbard model with attractive interactions.

Findings

Ground state is a charge density wave with long-range order.

All excitations are gapful, indicating an incompressible ground state.

Charge gap varies non-monotonically with interaction strength.

Abstract

We investigate low-energy excitations of the one-dimensional half-filled SU(4) Hubbard model with an attractive on-site interaction U < 0 using the density matrix renormalization group method as well as a perturbation theory. We find that the ground state is a charge density wave state with a long range order. The ground state is completely incompressible since all the excitations are gapful. The charge gap which is the same as the four-particle excitation gap is a non-monotonic function of U, while the spin gap and others increase with increasing |U| and have linear asymptotic behaviors.