First measurements of absolute branching fractions of the $\hat{I}{ž}_c^{+}$ baryon at Belle

Abstract

We present the first measurements of the absolute branching fractions of $\hat{I}{ž}_c^{+}$ decays into $\hat{I}{ž}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+}$ and $p{K}^{-}\ddot{I}{€}^{+}$ final states. Our analysis is based on a data set of $(772\pm 11)\times 10^6$ $B\bar{B}$ pairs collected at the $\hat{I}\yen (4S)$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. We measure the absolute branching fraction of ${\bar{B}}^0\to \bar{\hat{I}}{›}_c^{-}\hat{I}{ž}_c^{+}$ with the $\hat{I}{ž}_c^{+}$ recoiling against $\bar{\hat{I}}{›}_c^{-}$ in ${\bar{B}}^0$ decays resulting in $\mathcal{B}({\bar{B}}^0\to \bar{\hat{I}}{›}_c^{-}\hat{I}{ž}_c^{+})=[1.16\pm 0.42(stat.)\pm 0.15(syst.)]\times 10^{-3}$. We then measure the product branching fractions $\mathcal{B}({\bar{B}}^0\to \bar{\hat{I}}{›}_c^{-}\hat{I}{ž}_c^{+})\mathcal{B}(\hat{I}{ž}_c^{+}\to \hat{I}{ž}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+})$ and $\mathcal{B}({\bar{B}}^0\to \bar{\hat{I}}{›}_c^{-}\hat{I}{ž}_c^{+})\mathcal{B}(\hat{I}{ž}_c^{+}\to p{K}^{-}\ddot{I}{€}^{+})$. Dividing these product branching fractions by ${\bar{B}}^0\to \bar{\hat{I}}{›}_c^{-}\hat{I}{ž}_c^{+}$ yields: $\mathcal{B}(\hat{I}{ž}_c^{+}\to \hat{I}{ž}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+})=[2.86\pm 1.21(stat.)\pm 0.38(syst.)]\%$ and $\mathcal{B}(\hat{I}{ž}_c^{+}\to p{K}^{-}\ddot{I}{€}^{+})=[0.45\pm 0.21(stat.)\pm 0.07(syst.)]\%$. Our result for $\mathcal{B}(\hat{I}{ž}_c^{+}\to \hat{I}{ž}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+})$ can be combined with $\hat{I}{ž}_c^{+}$ branching fractions measured relative to $\hat{I}{ž}_c^{+}\to \hat{I}{ž}^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+}$ to set the absolute scale for many $\hat{I}{ž}_c^{+}$ branching fractions.

7 pages, 2 figures, accepted for publication as a Rapid Communication in Physical Review D