Observation of Three Resonant Structures in the Cross Section of e⁺e^-→π⁺π^- h_c

2025/04/05 by BESIII Collaboration, Ablikim, M., Achasov, M. N. +688 · 2 citations
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)

paper · doi:10.48550/arxiv.2504.04096

Abstract

Using e⁺e^- collision data collected with the BESIII detector operating at the Beijing Electron Positron Collider, the cross section of e⁺e^-→ π⁺π^- h_c is measured at 59 points with center-of-mass energy √(s) ranging from 4.009 to 4.950~GeV with a total integrated luminosity of 22.2~fb^-1. The cross section between 4.3 and 4.45~GeV exhibits a plateau-like shape and drops sharply around 4.5~GeV, which cannot be described by two resonances only. Three coherent Breit-Wigner functions are used to parameterize the √(s)-dependent cross section line shape. The masses and widths are determined to be M₁=(4223.6_-3.7-2.9^+3.6+2.6)~MeV/c², Γ₁=(58.5_-11.4-6.5^+10.8+6.7)~MeV, M₂=(4327.4_-18.8-9.3^+20.1+10.7)~MeV/c², Γ₂=(244.1_-27.1-18.3^+34.0+24.2)~MeV, and M₃=(4467.4_-5.4-2.7^+7.2+3.2)~MeV/c², Γ₃=(62.8_-14.4-7.0^+19.2+9.9)~MeV. The first uncertainties are statistical and the second are systematic. The inclusion of the relatively narrower third component proves crucial for reproducing the drop at around 4.5~GeV. The statistical significance of the three-resonance assumption over the two-resonance assumption is greater than 5σ.

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• Discovery of XYZ particles at the BESIII Experiment
• Dipionic transitions of Y(4500) to J/ψ

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