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arXiv 1605.09347cond-mat.stat-mechnlin.SI
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有限海森堡链的激发态关联

Excited state correlations of the finite Heisenberg chain

B. Pozsgay

摘要:

我们考虑有限XXZ和XXX海森堡自旋链的激发态中的短程关联。我们猜想,如果适当地改变结构的所谓物理部分,我们已知的因式分解基态关联的结果也可以应用于激发态。对于基态,我们推导出简单的代数表达式的物理部分,公式只使用基态贝特根作为输入。我们推测,如果用激发态的确切Bethe根来代替,同样的公式也可以应用于激发态。在XXZ链中,结果预计对所有状态都有效(除了某些需要正则化的奇异情况),而在XXX情况下,它们只适用于单态或群不变算子。对精确对角化和坐标Bethe Anastrophic计算的数值数据进行了测试,在所有情况下都发现了完美的一致性。在XXX的情况下,我们还得到了一个新的结果,最近邻相关$\{σ_1^zσ_2^z\}$,这是有效的非单态以及。我们的研究结果建立了一个桥梁之间的已知理论的因子相关性,和最近的构造块的TBA的描述。

英文摘要:

We consider short range correlations in excited states of the finite XXZ and XXX Heisenberg spin chains. We conjecture that the known results for the factorized ground state correlations can be applied to the excited states too, if the so-called physical part of the construction is changed appropriately. For the ground state we derive simple algebraic expressions for the physical part; the formulas only use the ground state Bethe roots as an input. We conjecture that the same formulas can be applied to the excited states as well, if the exact Bethe roots of the excited states are used instead. In the XXZ chain the results are expected to be valid for all states (except certain singular cases where regularization is needed), whereas in the XXX case they only apply to singlet states or group invariant operators. Our conjectures are tested against numerical data from exact diagonalization and coordinate Bethe Ansatz calculations, and perfect agreement is found in all cases. In the XXX case we also derive a new result for the nearest-neighbour correlator $\{σ_1^zσ_2^z\}$, which is valid for non-singlet states as well. Our results build a bridge between the known theory of factorized correlations, and the recently conjectured TBA-like description for the building blocks of the construction.

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