Threshold effects as the origin of $Y(4500)$ observed in $e^+e^-\to J/ψK^+K^-$

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Main Authors: Wang, Xiao-Yun, Wang, Liu-Lin, Liu, Xiao-Hai, Zhao, Qiang
Format: Preprint
Published: 2025
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author Wang, Xiao-Yun
Wang, Liu-Lin
Liu, Xiao-Hai
Zhao, Qiang
author_facet Wang, Xiao-Yun
Wang, Liu-Lin
Liu, Xiao-Hai
Zhao, Qiang
contents The BESIII collaboration has recently observed a resonant structure $Y(4500)$ in $e^{+}e^{-}\to J/ψK^{+}K^{-}$, whose origin remains unresolved. In this study, we analyze the cross section line shape of $e^{+}e^{-}\to J/ψK^{+}K^{-}$ by taking into account the $ψ(4415)$ state and intermediate charmed meson loops. By treating $ψ(4415)$ as both a pure $S$-wave state and $S$-$D$ mixed states, and introducing the $Z_{cs}^{(\prime)}$ resonance, we find that the $Y(4500)$ peak at $\sqrt{s}=4.5~\text{GeV}$ arises from the triangle singularity mechanism in the $Z_{cs}^{(\prime)}$-mediated rescattering processes, supporting its interpretation as a threshold effect rather than a conventional resonance.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23099
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Threshold effects as the origin of $Y(4500)$ observed in $e^+e^-\to J/ψK^+K^-$
Wang, Xiao-Yun
Wang, Liu-Lin
Liu, Xiao-Hai
Zhao, Qiang
High Energy Physics - Phenomenology
High Energy Physics - Experiment
The BESIII collaboration has recently observed a resonant structure $Y(4500)$ in $e^{+}e^{-}\to J/ψK^{+}K^{-}$, whose origin remains unresolved. In this study, we analyze the cross section line shape of $e^{+}e^{-}\to J/ψK^{+}K^{-}$ by taking into account the $ψ(4415)$ state and intermediate charmed meson loops. By treating $ψ(4415)$ as both a pure $S$-wave state and $S$-$D$ mixed states, and introducing the $Z_{cs}^{(\prime)}$ resonance, we find that the $Y(4500)$ peak at $\sqrt{s}=4.5~\text{GeV}$ arises from the triangle singularity mechanism in the $Z_{cs}^{(\prime)}$-mediated rescattering processes, supporting its interpretation as a threshold effect rather than a conventional resonance.
title Threshold effects as the origin of $Y(4500)$ observed in $e^+e^-\to J/ψK^+K^-$
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2510.23099