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

2025/10/27 by Wang, Xiao-Yun, Wang, Liu-Lin, Liu, Xiao-Hai +1
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2510.23099

Abstract

The BESIII collaboration has recently observed a resonant structure Y(4500) in e⁺e^-→ J/ψK⁺K^-, whose origin remains unresolved. In this study, we analyze the cross section line shape of e⁺e^-→ 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^(′) resonance, we find that the Y(4500) peak at √(s)=4.5~GeV arises from the triangle singularity mechanism in the Z_cs^(′)-mediated rescattering processes, supporting its interpretation as a threshold effect rather than a conventional resonance.

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