ϒ(5S) in the unquenched quark model

The observation of the [Formula: see text] state by Belle II Collaboration has sparked significant interest in the theoretical understanding of such states within the context of hadron physics. Considering the similar mass and the decay with, as well as the same quantum numbers [Formula: see text] with the [Formula: see text] state, which is referred to be the [Formula: see text] in PDG, in this work, we try to calculate the mass of the [Formula: see text] state. The model used to predict the high-energy spectrum of these states generally involves a constituent quark model, which can describe a variety of properties of hadrons containing heavy quarks. In the framework of the unquenched quark model, a coupled-channel calculation is employed to explore the effect of open-bottom meson–meson thresholds on the [Formula: see text] state. The hypothesis is that coupled-channel effects could be large enough to create new dynamically generated states, thus potentially explaining the nature of the [Formula: see text] state, as well as whether [Formula: see text] and [Formula: see text] is the same state. The results indicate that unquenched effects play a crucial role in explaining [Formula: see text] state, providing a plausible mechanism for its formation. Besides in our calculations, [Formula: see text] and [Formula: see text] may be two different states.