Recently, the LHCb Collaboration discovered the first doubly charmed baryon ${\mathrm{\Xi }}_{cc}^{++}=ccu$ at $3621.40\pm 0.78\mathrm{MeV}$, very close to our theoretical prediction. We use the same methods to predict a doubly bottom tetraquark $T(bb\overline{u}\overline{d})$ with $J^P=1^{+}$ at $10389\pm 12\mathrm{MeV}$, 215 MeV below the $B^{-}{\overline{B}}^{*0}$ threshold and 170 MeV below the threshold for decay to $B^{-}{\overline{B}}^0\gamma$. The $T(bb\overline{u}\overline{d})$ is therefore stable under strong and electromagnetic interactions and can only decay weakly, the first exotic hadron with such a property. On the other hand, the mass of $T(cc\overline{u}\overline{d})$ with $J^P=1^{+}$ is predicted to be $3882\pm 12\mathrm{MeV}$, 7 MeV above the $D^0{D}^{*+}$ threshold and 148 MeV above the $D^0{D}^{+}\gamma$ threshold. $T(bc\overline{u}\overline{d})$ with $J^P=0^{+}$ is predicted at $7134\pm 13\mathrm{MeV}$, 11 MeV below the ${\overline{B}}^0{D}^0$ threshold. Our precision is not sufficient to determine whether $bc\overline{u}\overline{d}$ is actually above or below the threshold. It could manifest itself as a narrow resonance just at threshold.

中文翻译：

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双重迷住的cc重子的发现暗示了Stablebbu·d·四夸克

最近，LHCb合作发现了第一个倍受迷住的重晶石 ${\mathrm{\Xi }}_{CC}^{++}=CCü$ 在 $3621.40\pm 0.78\mathrm{电动汽车}$，非常接近我们的理论预测。我们使用相同的方法来预测双底四夸克$Ť（bb\overline{ü}\overline{d}）$ 和 ${Ĵ}^P={\mathrm{1个}}^{+}$ 在 $10389\pm 12\mathrm{电动汽车}$低于215 MeV ${乙}^{-}{\overline{乙}}^{*0}$ 阈值和低于170 MeV的阈值以衰减至 ${乙}^{-}{\overline{乙}}^0\gamma$。这$Ť（bb\overline{ü}\overline{d}）$因此，它在强电磁作用下是稳定的，并且只能弱衰变，这是第一个具有这种性质的奇异强子。另一方面，$Ť（CC\overline{ü}\overline{d}）$ 和 ${Ĵ}^P={\mathrm{1个}}^{+}$ 预计是 $3882\pm 12\mathrm{电动汽车}$，高于7 MeV $d^0{d}^{*+}$ 阈值和148 MeV以上 $d^0{d}^{+}\gamma$ 临界点。 $Ť（bC\overline{ü}\overline{d}）$ 和 ${Ĵ}^P=0^{+}$ 预计在 $7134\pm 13\mathrm{电动汽车}$，低于11 MeV ${\overline{乙}}^0{d}^0$临界点。我们的精度不足以确定$bC\overline{ü}\overline{d}$实际上高于或低于阈值。它可能在阈值处表现为狭窄的共振。