Prediction of an $I(J^{P})=0(1^{-})$ $\bar{b}\bar{b}ud$ Tetraquark Resonance Close to the $B^\ast B^\ast$ Threshold Using Lattice QCD Potentials

Abstract

We use antistatic-antistatic potentials computed with lattice QCD and a coupled-channel Born-Oppenheimer approach to explore the existence of a $\bar{b} \bar{b} u d$ tetraquark resonance with quantum numbers $I(J^P) = 0(1^-)$. A pole in the $\mbox{T}$ matrix signals a resonance with mass $m = 2 m_B + 94.0^{+1.3}_{-5.4} \, \text{MeV}$ and decay width $\Gamma = 140^{+86}_{-66} \, \text{MeV}$, i.e. very close to the $B^\ast B^\ast$ threshold. We also compute branching ratios, which clearly indicate that this resonance is mainly composed of a $B^\ast B^\ast$ meson pair with a significantly smaller $B B$ contribution. By varying the potential matrix responsible for the coupling of the $B B$ and the $B^\ast B^\ast$ channel as well as the $b$ quark mass, we provide additional insights and understanding concerning the formation and existence of the resonance. We also comment on the importance of our findings and the main takeaways for a possible future full lattice QCD investigation of this $I(J^P) = 0(1^-)$ $\bar{b} \bar{b} u d$ tetraquark resonance.