Physicists map rare particle decay, opening window into matter's hidden asymmetries
Researchers using the BESIII detector have observed a particle decay process never before seen, revealing how exotic matter particles break fundamental symmetry rules. The finding could help scientists understand the subtle imbalances that allowed matter to dominate over antimatter in the early universe—a question with implications for physics-based technologies and fundamental theory validation.
Originaltitel: Observation of 𝜓(3686) → 𝛾𝜂(1405) via 𝜂(1405) → 𝑓<sub>0</sub>(980)𝜋<sup>0</sup>
<p>The decay 𝜓(3686) → 𝛾𝜋+𝜋−𝜋0 is studied using a sample of (2712.4 ±14.3) ×106 𝜓(3686) events collected with the BESIII detector. The decay 𝜂(1405) → 𝜋+𝜋−𝜋0 is observed for the first time in 𝜓(3686) decays via the intermediate state 𝑓0(980) and the product branching fraction ℬ(𝜓(3686) → 𝛾𝜂(1405))×ℬ(𝜂(1405) → 𝑓0(980)𝜋0)×ℬ(𝑓0(980) → 𝜋+𝜋−) is determined to be (3.77 ±0.43 ±0.30) ×10−7, where the first uncertainty is statistical and the second is systematic. The branching fraction of isospin-violating decay 𝜓(3686) → 𝛾𝑓1(1285) → 𝛾𝑓0(980)𝜋0 → 𝛾𝜋+𝜋−𝜋0 is determined to be (7.36 ±2.25 ±2.36) ×10−8 with statistical significance of 2.9𝜎. Since no 𝜂𝑐 signal is evident in either the 𝜋+𝜋−𝜋0 or 𝑓0(980)𝜋0 mass spectrum, upper limits are set to be ℬ(𝜓(3686) → 𝛾𝜂𝑐) ×ℬ(𝜂𝑐 → 𝜋+𝜋−𝜋0) <3.09 ×10−7 and ℬ(𝜓(3686) → 𝛾𝜂𝑐)×ℬ(𝜂𝑐 → 𝑓0(980)𝜋0)×ℬ(𝑓0(980) → 𝜋+𝜋−)<7.97×10−8 at 90% confidence level, respectively.</p>