Fig. 1: Detection of the double-Λ hypernuclear event using machine learning.

a The detection result of the event from the machine learning analysis pipeline. The left panel depicts the input emulsion image, acquired under an optical microscope with a 20× objective lens, and the right panel presents the model’s output, highlighting the event topology with a confidence score of 0.8. b Photograph and schematic diagram of the event. An incoming Ξ⁻ particle (red arrow) is captured at vertex A, producing a double-Λ hypernucleus (#1) and particle #3. Cascade decay (blue arrows) of double-Λ hypernucleus (#1) occurred at vertices B and C, with emitted particles #4 and #5 from B, and #6, #7, and #8 from C, all stopping in the emulsion. Track #7 is identified as a π⁻ particle, represented by a dashed line. Particle length and angle measurements are detailed in Table 1.