2025/05/05 by Jun-Zhang Wang, Wang, Jun-Zhang, Jian-Bo Cheng +8 · 1 citation
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum Chromodynamics and Particle Interactions #Advanced Condensed Matter Physics
paper · pdf · doi:10.48550/arxiv.2505.02742
Near-threshold exotic hadrons are usually associated with S-wave hadron-hadron dynamics, while higher partial waves are expected to be strongly suppressed by the centrifugal barrier. We show that this expectation can be overturned in the bottomonium sector. In a coupled-channel meson exchange framework combined with the complex scaling method, we find a JPC=1-- pole, denoted as Y(10650), generated dominantly by the P-wave B^* B^* interaction and located close to the B^* B^* threshold. This pole naturally accounts for the anomalous enhancement observed just above the opening of the B^* B^* threshold in e+e-→ B^* B^*. Once its production strength is fixed by this threshold enhancement, the corresponding cross sections of σ[e+e-→ Y(10650)→ B B^*] are predicted by the pole residues and phase-space factors, giving a characteristic dip-or-peak structure consistent with the available Belle (II) data. We further study the hidden-bottom transition Y(10650)→ Υ(2S)η through a near-threshold B^* B^* loop mechanism. The resulting O(10∼100~keV) width for Y(10650)→ Υ(2S)η is sufficient to account for the corresponding cross sections measured by Belle II. The simultaneous appearance of this state in open- and hidden-bottom channels provides a direct experimental path to test a P-wave near-threshold mechanism and makes Y(10650) a strong candidate for the first neutral isoscalar exotic bottomoniumlike state in the spectral gap between Υ(4S) and Υ(5S).