We compute the composition of the bottomonium $\mathrm{\Upsilon }(nS)$ states [including $\mathrm{\Upsilon }(10860)$] and the new $\mathrm{\Upsilon }(10753)$ resonance reported by Belle in terms of quarkonium and meson-meson components. We use a recently developed novel approach utilizing lattice QCD string breaking potentials for the study of resonances. This approach is based on the diabatic extension of the Born-Oppenheimer approximation and the unitary emergent wave method and allows us to compute the poles of the $\mathrm{S}$ matrix. We focus on $I=0$ bottomonium $S$ wave bound states and resonances, where the Schrödinger equation is a set of coupled differential equations. One of the channels corresponds to a confined heavy quark-antiquark pair $\overline{b}b$, and the others correspond to pairs of heavy-light mesons. In a previous study, only one meson-meson channel ${\overline{B}}^{(*)}{B}^{(*)}$ was considered. Now, we also include the closed strangeness channel ${\overline{B}}_s^{(*)}{B}_s^{(*)}$, extending our formalism significantly to have a more realistic description of bottomonium. We confirm the new Belle resonance $\mathrm{\Upsilon }(10753)$ as a dynamical meson-meson resonance with around 76% meson-meson content. Moreover, we identify $\mathrm{\Upsilon }(4S)$ and $\mathrm{\Upsilon }(10860)$ as states with both sizable quarkonium and meson-meson contents. With these results, we contribute to the clarification of ongoing controversies in the vector bottomonium spectrum.

• Received 8 September 2020
• Revised 23 February 2021
• Accepted 23 March 2021

DOI:https://doi.org/10.1103/PhysRevD.103.074507

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Published by the American Physical Society