We give heavy quark-diquark symmetry predictions for doubly heavy baryons andtetraquarks in light of the recent discovery of the $\Xi_{cc}^{++}$ by LHCb.For five excited doubly charm baryons that are predicted to lie below the$\Lambda_c D$ threshold, we give predictions for their electromagnetic andstrong decays using a previously developed chiral Lagrangian with heavyquark-diquark symmetry. Based on the mass of the $\Xi_{cc}^{++}$, the existenceof a doubly heavy bottom $I=0$ tetraquark that is stable to the strong andelectromagnetic decays has been predicted. If the mass of this state is below10405 MeV, as predicted in some models, we argue using heavy quark-diquarksymmetry that the $J^P=1^+$ $I=1$ doubly bottom tetraquark state will lie justbelow the open bottom threshold and likely be a narrow state as well. In thisscenario, we compute strong decay width for this state using a new Lagrangianfor tetraquarks which is related to the singly heavy baryon Lagrangian by heavyquark-diquark symmetry.
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机译：根据LHCb最近发现的$ \ Xi_ {cc} ^ {++} $，我们给出了双重质重子和四夸克的重夸克-双夸克对称性预测。对于五个兴奋的双重质重子，预计它们位于$$以下。 \ Lambda_c D $阈值，我们使用先前开发的具有重夸克-双夸克对称性的手性拉格朗日算子，对其电磁和强衰变进行了预测。基于$ \ Xi_ {cc} ^ {++} $的质量，已经预测到存在一个双重底部$ I = 0 $四夸克，它对强衰变和电磁衰变是稳定的。如某些模型所预测的，如果该状态的质量低于10405 MeV，我们使用重夸克-二夸克对称性认为$ J ^ P = 1 ^ + $ $ I = 1 $双底四夸克态将位于开放底限以下并且可能也处于狭窄状态。在这种情况下，我们使用新的Lagrangianfor四夸克，通过重夸克-diquark对称性，与单个重质重子Lagrangian关联，计算出该状态的强衰减宽度。
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