Rational $Q$-systems for integrable spin chains without $U(1)$ symmetry

Fuente: arXiv
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Autores principales: Jiang, Yunfeng, Liu, Yi-Chao, Miao, Yuan, Tan, Zi-Xi
Formato: Preprint
Publicado: 2025
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author Jiang, Yunfeng
Liu, Yi-Chao
Miao, Yuan
Tan, Zi-Xi
author_facet Jiang, Yunfeng
Liu, Yi-Chao
Miao, Yuan
Tan, Zi-Xi
contents The $Q$-system is an efficient method for finding complete physical solutions of Bethe ansatz equations, but so far its application has been confined to systems possessing $U(1)$ symmetry. We extend the rational $Q$-system framework to integrable spin chains without $U(1)$ symmetry, exemplified by the closed XXZ model with anti-diagonal twists and the open XXZ model with non-diagonal boundary fields. We demonstrate that the $Q$-system can be derived by combining $TQ$-relation with fusion relations of higher-spin transfer matrices. This yields $QQ$-relations analogous to the $U(1)$ symmetric case but incorporating additional inhomogeneous terms. We present numerical solutions that are validated against exact diagonalization, confirming that it generates all and exclusively physical solutions.
format Preprint
id arxiv_https___arxiv_org_abs_2512_01551
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Rational $Q$-systems for integrable spin chains without $U(1)$ symmetry
Jiang, Yunfeng
Liu, Yi-Chao
Miao, Yuan
Tan, Zi-Xi
High Energy Physics - Theory
The $Q$-system is an efficient method for finding complete physical solutions of Bethe ansatz equations, but so far its application has been confined to systems possessing $U(1)$ symmetry. We extend the rational $Q$-system framework to integrable spin chains without $U(1)$ symmetry, exemplified by the closed XXZ model with anti-diagonal twists and the open XXZ model with non-diagonal boundary fields. We demonstrate that the $Q$-system can be derived by combining $TQ$-relation with fusion relations of higher-spin transfer matrices. This yields $QQ$-relations analogous to the $U(1)$ symmetric case but incorporating additional inhomogeneous terms. We present numerical solutions that are validated against exact diagonalization, confirming that it generates all and exclusively physical solutions.
title Rational $Q$-systems for integrable spin chains without $U(1)$ symmetry
topic High Energy Physics - Theory
url https://arxiv.org/abs/2512.01551