Bound states of double-heavy tetraquarks are studied in a constituent quark model. Two bound states are found for isospin and spin-parity I(J^P ) = 0(1^+) in the bb\bar{u}\bar{d} channel. One is deeply bound and compact made of colored diquarks, while the other is shallow and extended as a BB^* molecule. The former agrees well with lattice QCD results. A systematic decrease in the binding energy is seen by replacing one of the heavy quarks to a lighter one. Altogether we find ten bound states. It is shown for the first time that hadrons with totally different natures emerge from a single Hamiltonian.

中文翻译：

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稳定的双重四夸克：光谱和结构

在组成夸克模型中研究双重四夸克的束缚态。在 bb\bar{u}\bar{d} 通道中发现了同位旋和自旋奇偶性 I(J^P ) = 0(1^+) 的两个束缚态。一个是由有色二夸克组成的紧密结合的紧密，而另一个是浅的并且作为BB^*分子延伸。前者与点阵 QCD 结果非常吻合。通过将一个重夸克替换为一个较轻的夸克，可以看到结合能的系统性下降。我们总共找到十个束缚态。首次表明，具有完全不同性质的强子从单个哈密顿量中出现。