First measurements of absolute branching fractions of the Ξc+ baryon at Belle

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We present the first measurements of the absolute branching fractions of ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}$ decays into ${\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ and $p{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ final states. Our analysis is based on a data set of $(772\ifmmode\pm\else\textpm\fi{}11)\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }B\overline{B}$ pairs collected at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with the Belle detector at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider. We measure the absolute branching fraction of ${\overline{B}}^{0}\ensuremath{\rightarrow}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}{\mathrm{\ensuremath{\Xi}}}_{c}^{+}$ with the ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}$ recoiling against ${\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}$ in ${\overline{B}}^{0}$ decays resulting in $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}{\mathrm{\ensuremath{\Xi}}}_{c}^{+})=[1.16\ifmmode\pm\else\textpm\fi{}0.42(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.15(\mathrm{syst}.)]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. We then measure the product branching fractions $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}{\mathrm{\ensuremath{\Xi}}}_{c}^{+})\mathcal{B}({\mathrm{\ensuremath{\Xi}}}_{c}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})$ and $\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}{\mathrm{\ensuremath{\Xi}}}_{c}^{+})\mathcal{B}({\mathrm{\ensuremath{\Xi}}}_{c}^{+}\ensuremath{\rightarrow}p{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})$. Dividing these product branching fractions by ${\overline{B}}^{0}\ensuremath{\rightarrow}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}{\mathrm{\ensuremath{\Xi}}}_{c}^{+}$ yields $\mathcal{B}({\mathrm{\ensuremath{\Xi}}}_{c}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})=[2.86\ifmmode\pm\else\textpm\fi{}1.21(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.38(\mathrm{syst}.)]%$ and $\mathcal{B}({\mathrm{\ensuremath{\Xi}}}_{c}^{+}\ensuremath{\rightarrow}p{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})=[0.45\ifmmode\pm\else\textpm\fi{}0.21(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.07(\mathrm{syst}.)]%$. Our result for $\mathcal{B}({\mathrm{\ensuremath{\Xi}}}_{c}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})$ can be combined with ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}$ branching fractions measured relative to ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ to set the absolute scale for many ${\mathrm{\ensuremath{\Xi}}}_{c}^{+}$ branching fractions.

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