Observation of resonant contribution to the e⁺e^-→ Ω^-Ω⁺ around 4.2 GeV and evidence of ψ(3770)→ Ω^-Ω⁺

2025/05/06 by BESIII Collaboration, Ablikim, M., Achasov, M. N. +635
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)

paper · doi:10.48550/arxiv.2505.03180

Abstract

Using e⁺e^- collision data corresponding to a total integrated luminosity of 22.7 fb^-1, collected at center-of-mass energies between 3.7 and 4.7 GeV with the BESIII detector, we present a measurement of energy-dependent cross sections and effective form factors for the process of e⁺e^-→ Ω^-Ω⁺. By conducting a fit to the cross sections of e⁺e^-→ Ω^-Ω⁺ considering the continuum and resonant contributions, a clear resonant structure in the spectrum around 4.2 GeV is observed for the first time with a statistical significance exceeding 10σ, and it can be well described with the line shape of the Y(4230) and Y(4320) observed in e⁺e^-→ π⁺π^-J/ψ. Evidence for the decay ψ(3770) → Ω^-Ω⁺ is observed with a statistical significance of 4.4σ by analyzing the measured cross sections together with earlier BESIII results, and the branching fraction is firstly measured to be (4.0±1.0±0.6) × 10^-5, where the first uncertainty is statistical and the second is systematic.

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