Measurements of ${\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}\overline{p}{K}^{+}{\ensuremath{\Sigma}}^{0}$ and ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}\overline{p}{K}^{+}\ensuremath{\Lambda}$

Measurements of $ψ^{'} \to \bar{p} K^{+} Σ^{0}$ and $χ_{c J} \to \bar{p} K^{+} Λ$

M. Ablikim et al. (BESIII Collaboration)

Phys. Rev. D 87, 012007 – Published 18 January 2013

Abstract

Using a sample of $1.06 \times 10^{8}$ $ψ^{'}$ mesons collected with the BESIII detector at the BEPCII $e^{+} e^{-}$ collider and $χ_{c J}$ mesons produced via radiative transitions from the $ψ^{'}$ , we report the first observation for $ψ^{'} \to \bar{p} K^{+} Σ^{0} + c . c .$ (charge conjugate), as well as improved measurements for the $χ_{c J}$ hyperon decays $χ_{c J} \to \bar{p} K^{+} Λ + c . c .$ The branching fractions are measured to be $B (ψ^{'} \to \bar{p} K^{+} Σ^{0} + c . c .) = (1.67 \pm 0.13 \pm 0.12) \times 10^{- 5}$ , $B (χ_{c 0} \to \bar{p} K^{+} Λ + c . c .) = (13.2 \pm 0.3 \pm 1.0) \times 10^{- 4}$ , $B (χ_{c 1} \to \bar{p} K^{+} Λ + c . c .) = (4.5 \pm 0.2 \pm 0.4) \times 10^{- 4}$ , and $B (χ_{c 2} \to \bar{p} K^{+} Λ + c . c .) = (8.4 \pm 0.3 \pm 0.6) \times 10^{- 4}$ , where the first error is statistical, and the second is systematic. In the decay of $χ_{c 0} \to \bar{p} K^{+} Λ + c . c .$ , an anomalous enhancement near threshold is observed in the invariant mass distribution of $\bar{p} Λ + c . c .$ , which cannot be explained by phase space.