Measurement of the singly Cabibbo-suppressed decay Λc⁺→ pη with deep learning

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A bstract Using 4 . 5 fb − 1 of e + e − collision data collected with the BESIII detector at center-of-mass energies from 4.600 to 4.699 GeV, we report a measurement of the singly Cabibbo-suppressed decay Λc⁺→ pη Λ c + → p η ′ with the single-tag method. To effectively distinguish the signal from the large backgrounds, we exploit a deep-learning classifier built on a Transformer-based neural network. Extensive validation and uncertainty quantification are carried out. The Λc⁺→ pη Λ c + → p η ′ signal is observed with a statistical significance of 3 . 1 σ . The ratio of branching fractions of B(Λc⁺→ pη^)/B(Λc⁺→ pω )=0.55± 0.22± 0.05 B Λ c + → p η ′ / B Λ c + → pω = 0.55 ± 0.22 ± 0.05 is obtained, where the first uncertainty is statistical and the second systematic.