We consider the problem of computing dynamic correlation functions of quantum integrable models employing the thermodynamic form-factor approach. Specifically, we focus on correlations of local operators that conserve the number of particles and consider the two-particle–hole contribution to their two-point functions. With the method developed being generally applicable to any finite energy and entropy state, our primary focus is on the thermal states. To exemplify this approach, we chose the Lieb–Liniger model and study the leading contribution from two-particle–hole excitations at small momenta to the dynamic density–density correlation function. We also consider analogous contributions to two-point functions of higher local conserved densities and currents present in integrable theories.

我们考虑使用热力学形状因数方法计算量子可积模型的动态相关函数的问题。具体来说，我们专注于保留粒子数量的本地算子的相关性，并考虑两粒子-空穴对其两点函数的贡献。随着开发的方法普遍适用于任何有限的能量和熵态，我们的主要重点是热态。为了举例说明这种方法，我们选择了Lieb–Liniger模型，并研究了小时刻两粒子-空穴激励对动态密度-密度相关函数的主要贡献。我们还考虑了对可积理论中存在的较高局部守恒密度和电流的两点函数的类似贡献。