Peer-reviewedCC BYSciPost Physics
Solving the 4 × 4 quantum Yang-Baxter equation
- 1Trinity College Dublin
Abstract
In this paper, we complete the classification of 4×4 4 × 4 analytic solutions of the Yang–Baxter equation. Regular solutions were recently classified and in this paper we find the remaining non-regular solutions. We present several new solutions, then consider regular and non-regular Lax operators and study their relation to the quantum Yang–Baxter equation. We show that for regular solutions there is a correspondence, which is lost in the non-regular case. In particular, we find non-regular Lax operators whose R R -matrix from the fundamental commutation relations is regular but does not satisfy the Yang-Baxter equation. These R R -matrices satisfy a modified Yang–Baxter equation instead.
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BibTeX
@article{leeuw2026solving,
title = {{Solving the $4 \times 4$ quantum Yang-Baxter equation}},
author = {Marius de Leeuw and Vera Posch},
journal = {SciPost Physics},
year = {2026},
month = sep,
doi = {10.21468/scipostphys.21.3.060},
url = {https://doi.org/10.21468/scipostphys.21.3.060},
note = {CC BY},
}
RIS
TY - JOUR
TI - Solving the 4 × 4 quantum Yang-Baxter equation
AU - Marius de Leeuw
AU - Vera Posch
PY - 2026
DA - 2026/09/10
JO - SciPost Physics
DO - 10.21468/scipostphys.21.3.060
UR - https://doi.org/10.21468/scipostphys.21.3.060
AB - In this paper, we complete the classification of 4×4 4 × 4 analytic solutions of the Yang–Baxter equation. Regular solutions were recently classified and in this paper we find the remaining non-regular solutions. We present several new solutions, then consider regular and non-regular Lax operators and study their relation to the quantum Yang–Baxter equation. We show that for regular solutions there is a correspondence, which is lost in the non-regular case. In particular, we find non-regular Lax operators whose R R -matrix from the fundamental commutation relations is regular but does not satisfy the Yang-Baxter equation. These R R -matrices satisfy a modified Yang–Baxter equation instead.
SN - 2542-4653
ER -