Boundary bound states for the open Hubbard chain with boundary fields

TL;DR

This paper investigates boundary effects in the open Hubbard chain with boundary fields, revealing boundary-bound states through Bethe ansatz solutions and showing their presence in the ground state at half-filling.

Contribution

It provides explicit boundary string solutions of the Bethe ansatz equations and demonstrates their role in the ground state of the model.

Findings

Boundary string solutions localized at the boundary

Boundary strings are present in the ground state at half-filling

Wave functions decay exponentially away from the boundary

Abstract

The boundary effects in the open Hubbard chain with boundary fields are studied. The boundary string solutions of the Bethe ansatz equations that give rise to a wave functions localized at the boundary and exponentially decreasing away from the boundary are provided. In particular, it is shown that the correct ground state of the model at half-filling contains the boundary strings.