6533b7d2fe1ef96bd125f3fa

RESEARCH PRODUCT

Theoretical study of the Ξ(1620) and Ξ(1690) resonances in Ξc→π+MB decays

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Nonleptonic weak decays of ${\mathrm{\ensuremath{\Xi}}}_{c}$ into ${\ensuremath{\pi}}^{+}$ and a meson $(M)$-baryon $(B)$ final state, $MB$, are analyzed from the viewpoint of probing $S=\ensuremath{-}2$ baryon resonances, i.e., $\mathrm{\ensuremath{\Xi}}(1620)$ and $\mathrm{\ensuremath{\Xi}}(1690)$, of which spin-parity and other properties are not well known. We argue that the weak decay of ${\mathrm{\ensuremath{\Xi}}}_{c}$ is dominated by a single quark-line diagram, preferred by the Cabibbo-Kobayashi-Maskawa coefficient, color recombination factor, the diquark correlation, and the kinematical condition. The decay process has an advantage of being free from meson resonances in the ${\ensuremath{\pi}}^{+}M$ invariant mass distribution. The invariant mass distribution of the meson-baryon final state is calculated with three different chiral unitary approaches, assuming that the $\mathrm{\ensuremath{\Xi}}(1620)$ and $\mathrm{\ensuremath{\Xi}}(1690)$ resonances have ${J}^{P}=1/{2}^{\ensuremath{-}}$. It is found that a clear peak for the $\mathrm{\ensuremath{\Xi}}(1690)$ is seen in the $\ensuremath{\pi}\mathrm{\ensuremath{\Xi}}$ and $\overline{K}\mathrm{\ensuremath{\Lambda}}$ spectra. We also suggest that the ratios of the $\ensuremath{\pi}\mathrm{\ensuremath{\Xi}},\overline{K}\mathrm{\ensuremath{\Lambda}}$, and $\overline{K}\mathrm{\ensuremath{\Sigma}}$ final states are useful to distinguish whether the peak is originated from the $\mathrm{\ensuremath{\Xi}}(1690)$ resonance or it is a $\overline{K}\mathrm{\ensuremath{\Sigma}}$ threshold effect.