Observation of New States Decaying into ${\ensuremath{\Lambda}}_{c}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ and ${\ensuremath{\Lambda}}_{c}^{+}{K}_{S}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}$

Observation of New States Decaying into $Λ_{c}^{+} K^{-} π^{+}$ and $Λ_{c}^{+} K_{S}^{0} π^{-}$

R. Chistov et al. (Belle Collaboration)

Phys. Rev. Lett. 97, 162001 – Published 17 October 2006

Abstract

We report the first observation of two charmed strange baryons that decay into $Λ_{c}^{+} K^{-} π^{+}$ . The broader of the two states is measured to have a mass of $2978.5 \pm 2.1 \pm 2.0 MeV / c^{2}$ and a width of $43.5 \pm 7.5 \pm 7.0 MeV / c^{2}$ . The mass and width of the narrow state are measured to be $3076.7 \pm 0.9 \pm 0.5 MeV / c^{2}$ and $6.2 \pm 1.2 \pm 0.8 MeV / c^{2}$ , respectively. We also perform a search for the isospin partner states that decay into $Λ_{c}^{+} K_{S}^{0} π^{-}$ and observe a significant signal at the mass of $3082.8 \pm 1.8 \pm 1.5 MeV / c^{2}$ . The data used for this analysis were accumulated at or near the $Υ (4 S)$ resonance, using the Belle detector at the $e^{+} e^{-}$ asymmetric-energy collider KEKB. The integrated luminosity of the data sample used is $461.5 {fb}^{- 1}$ .