Threshold effects as the origin of Y ( 4500 ) observed in e + e − → J / ψ K + K −
Abstract
The BESIII Collaboration has recently observed a resonant structure Y ( 4500 ) in e + e − → J / ψ K + K − , whose origin remains unresolved. In this study, we analyze the cross section line shape of e + e − → J / ψ K + 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 c s ( ′ ) resonance, we find that the Y ( 4500 ) peak at s = 4.5 GeV arises from the triangle singularity mechanism in the Z c s ( ′ ) -mediated rescattering processes, supporting its interpretation as a threshold effect rather than a conventional resonance.
Fields of Study & Subjects
Quantum Chromodynamics and Particle Interactions
Astrophysics and Star Formation Studies
Astronomy and Astrophysical Research
Publication details
- Journal / source
- Physical review. D/Physical review. D.
- Publisher
- American Physical Society (APS)
- Volume
- 113
- Issue
- 1
- Publication date
- 7 January 2026
- Language
- EN