Many candidates of the so-called exotic hadrons have been observed experimentally and most of them are located close to the threshold of a pair of hadrons. The general behavior of the near-threshold line shapes of invariant mass distributions is discussed. To be precise, the threshold cusp can show up as a peak only for channels with attractive interaction, and the width of the cusp is inversely proportional to the reduced mass relevant for the threshold. We argue that there should be (near-)threshold structures for any pair of heavy-quark and heavy-antiquark hadrons, which have attractive interaction at threshold, in the invariant mass distribution of a heavy quarkonium and light hadrons that couple to that open-flavor hadron pair. Predictions of the possible pairs that have near-threshold peaks are given for the ground state heavy hadrons based on the interaction saturated by vector mesons. We also give a survey of the possible hadronic molecules composed of a pair of charmed-anticharmed hadrons by solving the Bethe-Salpeter equation with constant interactions and the experimental candidates of hadronic molecules fit this spectrum well.

许多所谓的外来强子的候选者已被实验观察到，其中大多数位于一对强子的阈值附近。讨论了不变质量分布的近阈值线形状的一般行为。准确地说，阈值尖峰只能显示为具有吸引力相互作用的通道的峰值，并且尖峰的宽度与与阈值相关的减少质量成反比。我们认为，在重夸克和轻强子的不变质量分布中，任何一对重夸克和重反夸克强子都应该有（近）阈值结构，它们在阈值处具有吸引力的相互作用。味强子对。基于矢量介子饱和的相互作用，对基态重强子可能具有接近阈值峰值的预测给出了预测。我们还通过求解具有恒定相互作用的 Bethe-Salpeter 方程，对由一对迷人-反魅力强子组成的可能强子分子进行了调查，并且强子分子的实验候选者很好地拟合了该光谱。