From the Hubbard to the SO(5) Ladder: A Numerical Study

TL;DR

This paper investigates the evolution of low energy excitations in a two-leg Hubbard ladder as it transitions to an SO(5) symmetric model, revealing approximate symmetry in the pure Hubbard case through numerical methods.

Contribution

It provides a numerical analysis of the Hubbard ladder's excitation spectrum and its evolution towards an exact SO(5) symmetric model.

Findings

Low energy excitations exhibit approximate SO(5) symmetry in the Hubbard ladder.

The spectrum evolves smoothly as the model transitions to the SO(5) symmetric point.

Numerical techniques confirm the symmetry properties of the low energy states.

Abstract

The Hubbard Hamiltonian on a two-leg ladder is studied numerically using quantum Monte Carlo and Exact Diagonalization techniques. A rung interaction, $V$, is turned on such that the resulting model has an exact SO(5) symmetry when $V=-U$. The evolution of the low energy excitation spectrum is presented from the pure Hubbard ladder to the SO(5) ladder. It is shown that the low energy excitations in the pure Hubbard ladder have an approximate SO(5) symmetry.