Physicists nail down rare particle decay with unprecedented precision
Researchers at China's BESIII detector have measured a subatomic decay process with record accuracy, reducing measurement uncertainty to less than 2.5%. The work improves our understanding of fundamental particle interactions and validates experimental techniques that could refine future discoveries in high-energy physics.
Originaltitel: Measurement of the branching fraction of the decay <em>J</em>/ψ → <em>p</em><em>p<</em>over-bar>η
<p>A high-precision measurement of the branching fraction of the decay J/ψ → pp<over bar>η is performed using (10 087 ± 44) x 10<sup>6</sup> J/ψ events recorded by the BESIII detector at the BEPCII storage ring. The branching fractions of the two decays J/ψ → pp<over bar>η(η → γγ) and J/ψ → pp<over bar>η(η → π<sup>+</sup>π<sup>-</sup>π<sup>0</sup>) are measured individually to be <em>B</em>(J/ψ → pp<over bar>η(η → γγ)) = (1.480 ± 0.001 ± 0.024) x 10<sup>-3</sup> and <em>B</em>(J/ψ → pp<over bar>η(η → π<sup>+</sup>π<sup>-</sup>π<sup>0</sup>) = (1.557 ± 0.003 ± 0.038) x 10<sup>-3</sup>, where the first uncertainties are statistical and the second systematic. Both results are compatible within their uncorrelated systematic uncertainties. The combined result is B(J/ψ → pp<over bar>η) = (1.495 ± 0.001 ± 0.023) x 10<sup>-3</sup>, where the first uncertainty is the combined statistical uncertainty and the second one the combined systematic uncertainty of both analyses, incorporating correlations between them. In addition, the pp<over bar> threshold region is investigated for a potential threshold enhancement, and no evidence for one is observed.</p>