Double-bottom centrifugal-barrier molecules dancing with four quarks
Motivated by the recent Belle II measurement of the open-bottom cross section, we perform a systematic study of the double-bottom molecular tetraquark spectrum, including both $S$-wave and $P$-wave configurations. Using the one-boson-exchange potential and the complex scaling method, we investigate the $B^{(*)}\bar{B}^*$ and $B^{(*)}B^*$ systems and predict several bound states and resonances. Our analysis reveals a rich spectrum, including $B\bar{B}^*$ ($0(1^{++})$, $0(0^{-+})$), $B^*\bar{B}^*$ ($0(2^{++})$, $0(0^{-+})$, $0(1^{--})$), $BB^*$ ($0(1^+)$), and $B^*B^*$ ($0(1^+)$) bound states, as well as $B\bar{B}^*$ ($0(1^{--})$, $0(2^{--})$), $B^*\bar{B}^*$ ($0(3^{--})$), $BB^*$ ($0(0^-)$), and $B^*B^*$ ($0(1^-)$, $0(2^-)$) resonances. Our results provide theoretical support for the existence of double-bottom tetraquarks and deliver key benchmarks for future searches at LHCb, Belle II, and other experiments.