Observation of the decays $B^{+}\to \hat{I}{\pounds }_c(2455{)}^{++}\overline{\hat{I}}{ž}_c^{-}$ and $B^0\to \hat{I}{\pounds }_c(2455{)}^0\overline{\hat{I}}{ž}_c^0$

Abstract

We report the first observation of the two-body baryonic decays $B^{+}\to \hat{I}{\pounds }_c(2455{)}^{++}\overline{\hat{I}}{ž}_c^{-}$ and $B^0\to \hat{I}{\pounds }_c(2455{)}^0\overline{\hat{I}}{ž}_c^0$ with significances of $7.3\ddot{I}ƒ$ and $6.2\ddot{I}ƒ$, respectively, including statistical and systematic uncertainties. The branching fractions are measured to be $\mathcal{B}(B^{+}\to \hat{I}{\pounds }_c(2455{)}^{++}\overline{\hat{I}}{ž}_c^{-})=(5.74\pm 1.11\pm 0.42_{-1.53}^{+2.47})\times 10^{-4}$ and $\mathcal{B}(B^0\to \hat{I}{\pounds }_c(2455{)}^0\overline{\hat{I}}{ž}_c^0)=(4.83\pm 1.12\pm 0.37_{-0.60}^{+0.72})\times 10^{-4}$. The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the absolute branching fractions of $\overline{\hat{I}}{ž}_c^{-}$ or $\overline{\hat{I}}{ž}_c^0$ decays. The data samples used for this analysis have integrated luminosities of 711~${\mathrm{fb}}^{-1}$ and 365~${\mathrm{fb}}^{-1}$, and were collected at the $\hat{I}\yen (4S)$ resonance by the Belle and Belle~II detectors operating at the KEKB and SuperKEKB asymmetric-energy $e^{+}{e}^{-}$ colliders, respectively.