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

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′ 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′ signal is observed with a statistical significance of 3.1σ. The ratio of branching fractions of BΛc+→pη′/BΛc+→pω=0.55±0.22±0.05 is obtained, where the first uncertainty is statistical and the second systematic.