Boundary S matrix of an open XXZ spin chain with nondiagonal boundary terms

TL;DR

This paper computes boundary scattering amplitudes for an open XXZ spin chain with nondiagonal boundary terms and relates lattice boundary parameters to IR boundary sine-Gordon parameters.

Contribution

It provides a solution for the boundary S matrix of an open XXZ chain with arbitrary boundary parameters at roots of unity, connecting lattice and IR parameters.

Findings

Boundary scattering amplitudes for one-hole states calculated

Relations established between lattice and IR boundary parameters

Results applicable to integrable quantum spin chains

Abstract

Using a recently proposed solution for an open antiferromagnetic spin-1/2 XXZ quantum spin chain with N (even) spins and two arbitrary boundary parameters at roots of unity, we compute the boundary scattering amplitudes for one-hole states. We also deduce the relations between the lattice boundary parameters appearing in the spin-chain Hamiltonian and the IR (infrared) parameters that appear in the boundary sine-Gordon S matrix.