Physicists map exotic particle decay, refining understanding of matter's building blocks
Researchers using China's BESIII detector have measured how a J/psi particle decays into rare combinations of other particles, revealing previously unmapped excited states of lambda baryons. The precision measurements advance fundamental physics knowledge that underpins next-generation particle detector design and validates theoretical models used across high-energy physics research.
Originaltitel: Amplitude analysis and branching fraction measurement of J/ψ → ΛΣ<sup>0</sup><over-bar>η + c.c.
<p>Based on a sample of (10087±44) x 10<sup>6</sup> J/ψ events collected with the BESIII detector, a partial-wave analysis of J/ψ → ΛΣ<sup>0</sup><over bar>η+c.c. is performed for the first time. The dominant contributions are found to be excited Λ states with J<sup>P</sup> = 1/2<sup>-</sup> and J<sup>P</sup> = 1/2<sup>+</sup> in the ηΛ mass spectra. The measured masses and widths are M = 1668.8 ± 3.1 ± 21.2 MeV/c<sup>2</sup> and Γ = 52.7 ± 4.2 ± 17.8 MeV for the Λ(1670), and M = 1881.5 ±16.5 ± 20.3 MeV/c<sup>2</sup> and Γ = 82.4 ± 18.2 ± 8.9 MeV for the Λ(1810), respectively. The branching fraction is determined to be <em>B</em>(J/ψ → ΛΣ<sup>0</sup><over bar> + c.c) = (3.44 ± 0.11 ± 0.13) x 10<sup>-5</sup>. The first uncertainties are statistical and the second systematic.</p>