$\Upsilon(5S)$ in the unquenched quark model
Abstract
The observation of the 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 with the state, which is referred to be the in PDG, in this work, we try to calculate the mass of the 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 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 state, as well as whether the and is the same state. The results indicate that unquenched effects play a crucial role in explaining the state, providing a plausible mechanism for its formation. Besides in our calculations, the and may be two different states.
Cite
@article{arxiv.2507.13882,
title = {$\Upsilon(5S)$ in the unquenched quark model},
author = {Xiaoyun Chen and Yue Tan and Yuan Chen and Xuejie Liu and Jialun Ping},
journal= {arXiv preprint arXiv:2507.13882},
year = {2025}
}