Search for doubly charmed baryons and study of charmed strange baryons at Belle

Abstract

We report results of a study of doubly charmed baryons and charmed strange baryons. The analysis is performed using a $980\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. We search for doubly charmed baryons ${\mathrm{\ensuremath{\Xi}}}_{cc}^{+(+)}$ with the ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}({\ensuremath{\pi}}^{+})$ and ${\mathrm{\ensuremath{\Xi}}}_{c}^{0}{\ensuremath{\pi}}^{+}({\ensuremath{\pi}}^{+})$ final states. No significant signal is observed. We also search for two excited charmed strange baryons, ${\mathrm{\ensuremath{\Xi}}}_{c}(3055{)}^{+}$ and ${\mathrm{\ensuremath{\Xi}}}_{c}(3123{)}^{+}$ with the ${\mathrm{\ensuremath{\Sigma}}}_{c}^{++}(2455){K}^{\ensuremath{-}}$ and ${\mathrm{\ensuremath{\Sigma}}}_{c}^{++}(2520){K}^{\ensuremath{-}}$ final states. The ${\mathrm{\ensuremath{\Xi}}}_{c}(3055{)}^{+}$ signal is observed with a significance of 6.6 standard deviations including systematic uncertainty, while no signature of the ${\mathrm{\ensuremath{\Xi}}}_{c}(3123{)}^{+}$ is seen. We also study properties of the ${\mathrm{\ensuremath{\Xi}}}_{c}(2645{)}^{+}$ and measure a width of $2.6\ifmmode\pm\else\textpm\fi{}0.2(\text{stat})\ifmmode\pm\else\textpm\fi{}0.4(\text{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, which is the first significant determination.