Evidence for $\ensuremath{\psi}\ensuremath{'}$ Decays into $\ensuremath{\gamma}{\ensuremath{\pi}}^{0}$ and $\ensuremath{\gamma}\ensuremath{\eta}$

Evidence for $ψ'$ Decays into $γ π^{0}$ and $γ η$

M. Ablikim et al. (BESIII Collaboration)

Phys. Rev. Lett. 105, 261801 – Published 20 December 2010

Abstract

The decays $ψ^{'} \to γ π^{0}$ , $γ η$ and $γ η^{'}$ are studied using data collected with the BESIII detector at the BEPCII $e^{+} e^{-}$ collider. The processes $ψ^{'} \to γ π^{0}$ and $ψ^{'} \to γ η$ are observed for the first time with signal significances of $4.6 σ$ and $4.3 σ$ , respectively. The branching fractions are determined to be $B (ψ^{'} \to γ π^{0}) = (1.58 \pm 0.40 \pm 0.13) \times 10^{- 6}$ , $B (ψ^{'} \to γ η) = (1.38 \pm 0.48 \pm 0.09) \times 10^{- 6}$ , and $B (ψ^{'} \to γ η^{'}) = (126 \pm 3 \pm 8) \times 10^{- 6}$ , where the first errors are statistical and the second ones systematic.