标题： 六顶点IRF模型及其量子自旋链的相关函数 显示英文标题

标题： Correlation functions of the six-vertex IRF model and its quantum spin chain

摘要： 我们考虑各向同性六顶点模型的围绕面相互作用版本。 相关的自旋链由两个耦合的海森堡自旋链组成，具有不同的边界扭曲。 该模型的相图和长距离关联在 [Nucl. Phys. B, 995 (2023) 116333] 中进行了研究。 在这里，我们通过非线性积分方程计算有限系统尺寸下该模型基态的短距离关联函数，并在热力学极限下进行计算。 这是可能的，因为该模型满足离散量子Knizhnik-Zamolodchikov (qKZ) 方程的面版本。 提出了密度矩阵的一个适当假设，形式为两个海森堡密度矩阵的直和，这使我们能够得到两站点函数$\omega(\lambda_1,\lambda_2)$的离散泛函方程。 由于对海森堡链关联函数分解的已知结果，我们能够计算出IRF模型最多四个站点的密度矩阵及其相关自旋链最多三个站点的密度矩阵。 显示英文摘要

摘要： We consider the interaction-round-a-face version of the isotropic six-vertex model. The associated spin chain is made of two coupled Heisenberg spin chains with different boundary twists. The phase diagram of the model and the long distance correlations were studied in [Nucl. Phys. B, 995 (2023) 116333]. Here, we compute the short-distance correlation functions of the model in the ground state for finite system sizes via non-linear integral equations and in the thermodynamic limit. This was possible since the model satisfies the face version of the discrete quantum Knizhnik-Zamolodchikov (qKZ) equation. A suitable ansatz for the density matrix is proposed in the form of a direct sum of two Heisenberg density matrices, which allows us to obtain the discrete functional equation for the two-site function $\omega(\lambda_1,\lambda_2)$. Thanks to the known results on the factorization of correlation functions of the Heisenberg chain, we are able to compute the density matrix of the IRF model for up to four sites and its associated spin chain for up to three sites.