# Observation of $\Xi \left(1620{\right)}^{0}$ and Evidence for $\Xi \left(1690{\right)}^{0}$ in ${\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}$ Decays

21 February 2019

Abstract: We report the first observation of the double strange baryon $\Xi \left(1620{\right)}^{0}$ in its decay to ${\Xi }^{-}{\pi }^{+}$ via ${\Xi }_{c}^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}$ decays based on a $980\text{}\text{}{\mathrm{fb}}^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{-}$ collider. The mass and width are measured to be $1610.4±6.0\left(\text{stat}{\right)}_{-4.2}^{+6.1}\text{}\left(\text{syst}\right)\text{}\text{}\mathrm{MeV}/{c}^{2}$ and $59.9±4.8\left(\text{stat}{\right)}_{-7.1}^{+2.8}\left(\text{syst}\right)\text{}\text{}\mathrm{MeV}$, respectively. We obtain $4.0\sigma$ evidence of the $\Xi \left(1690{\right)}^{0}$ with the same data sample. These results shed light on the structure of hyperon resonances with strangeness $S=-2$.

Published in: Physical Review Letters 122 (2019)