Observation of the Singly Cabibbo-Suppressed Decay $\hat{I}{›}_c^{+}\to p\ddot{I}{€}^0$

Abstract

Utilizing 4.5${\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected with the BESIII detector at the BEPCII collider at center-of-mass energies between 4.600 and 4.699 GeV, the first observation of the singly Cabibbo-suppressed decay $\hat{I}{›}_c^{+}\to p\ddot{I}{€}^0$ is presented, with a statistical significance of $5.4\ddot{I}ƒ$. The ratio of the branching fractions of $\hat{I}{›}_c^{+}\to p\ddot{I}{€}^0$ and $\hat{I}{›}_c^{+}\to p\hat{I}\cdot$ is measured as $\mathcal{B}(\hat{I}{›}_c^{+}\to p\ddot{I}{€}^0)/\mathcal{B}(\hat{I}{›}_c^{+}\to p\hat{I}\cdot )=(0.120\pm 0.026_{stat.}\pm 0.007_{syst.})$. This result resolves the longstanding discrepancy between earlier experimental searches, providing both a decisive conclusion and valuable input for QCD-inspired theoretical models. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish the signal from the prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

9 pages, 4 figures