Generic boundary scattering in the open XXZ chain

TL;DR

This paper derives an exact boundary S-matrix for the open critical XXZ spin chain with general boundary conditions, confirming previous results through a Bethe ansatz approach.

Contribution

It provides a straightforward method to compute the boundary S-matrix for the open XXZ chain with mixed boundary conditions, extending existing results.

Findings

Exact boundary S-matrix derived for the open XXZ chain

Results match previous findings by Ghoshal and Zamolodchikov

Applicable to both diagonal and non-diagonal boundary entries

Abstract

The open critical XXZ spin chain with a general right boundary and a trivial diagonal left boundary is considered. Within this framework we propose a simple computation of the exact generic boundary S-matrix (with diagonal and non-diagonal entries), starting from the `bare' Bethe ansatz equations. Our results coincide with the ones obtained by Ghoshal and Zamolodchikov, after assuming suitable identifications of the bulk and boundary parameters.