Boundary S Matrix for the XXZ Chain

TL;DR

This paper calculates the boundary S matrix for the open XXZ spin-1/2 chain with boundary magnetic fields in the noncritical regime using Bethe Ansatz, confirming previous vertex-operator results.

Contribution

It provides an explicit Bethe Ansatz computation of the boundary S matrix for the XXZ chain with diagonal boundary fields, matching known vertex-operator results.

Findings

Boundary S matrix expressed in terms of q-gamma functions

Results agree with previous vertex-operator calculations

Applicable in the noncritical regime (Delta > 1)

Abstract

We compute by means of the Bethe Ansatz the boundary S matrix for the open anisotropic spin-1/2 chain with diagonal boundary magnetic fields in the noncritical regime (Delta > 1). Our result, which is formulated in terms of q-gamma functions, agrees with the vertex-operator result of Jimbo et al.