Physicists map rare particle decays, revealing new quantum behavior
Researchers have measured how an exotic particle called hc decays into simpler particles—a first for several decay pathways. These measurements refine our understanding of quantum mechanics and could inform future particle detector designs, though applications remain years away.
Originaltitel: Measurements of the branching fractions of the <em>P</em>-wave charmonium spin-singlet state <em>h<sub>c</sub></em>(<sup>1</sup><em>P</em><sub>1</sub>) → <em>h</em><sup>+</sup><em>h</em><sup>-</sup>π<sup>0</sup>/η
<p>Based on (2712.4 ± 14.3) x 10<sup>6</sup> ψ(3686) events, we investigate four hadronic decay modes of the <em>P</em>-wave charmonium spin-singlet state h<sub>c</sub>(<sup>1</sup>P<sub>1</sub>) → h<sup>+</sup>h<sup>-</sup>π<sup>0</sup>/η(h =π or K) via the process ψ(3686) → π<sup>0</sup>h<sub>c</sub> at BESIII. The h<sub>c</sub> → π<sup>+</sup>π<sup>-</sup>π<sup>0</sup> decay is observed with a significance of 9.6σ after taking into account systematic uncertainties. Evidences for h<sub>c</sub> → K<sup>+</sup>K<sup>-</sup>π<sup>0</sup> and h<sub>c</sub> → K<sup>+</sup>K<sup>-</sup>η are found with significances of 3.5σ and 3.3σ, respectively, after considering the systematic uncertainties. The branching fractions of these decays are measured to be <em>B</em>(h<sub>c</sub> → π<sup>+</sup>π<sup>-</sup>π<sup>0</sup>) = (1.36 ± 0.16 ± 0.14)x10<sup>-3</sup>, <em>B</em>(h<sub>c</sub> → K<sup>+</sup>K<sup>-</sup>π<sup>0</sup>) = (3.26 ± 0.84 ± 0.36) x 10<sup>-4</sup>, and <em>B</em>(h<sub>c</sub> → K<sup>+</sup>K<sup>-</sup>η) = (3.13 ± 1.08 ± 0.38) x 10<sup>-4</sup>, where the first uncertainties are statistical and the second are systematic. No significant signal of h<sub>c</sub> → π<sup>+</sup>π<sup>-</sup>η is found, and the upper limit of its decay branching fraction is determined to be <em>B</em>(h<sub>c</sub> → π<sup>+</sup>π<sup>-</sup>η) < 4.0 x 10<sup>-4</sup> at the 90% confidence level.</p>