Charmonium decays to $\ensuremath{\gamma}{\ensuremath{\pi}}^{0}$, $\ensuremath{\gamma}\ensuremath{\eta}$, and $\ensuremath{\gamma}{\ensuremath{\eta}}^{\ensuremath{'}}$

Rapid Communication

Charmonium decays to $γ π^{0}$ , $γ η$ , and $γ η^{'}$

T. K. Pedlar et al. (CLEO Collaboration)

Phys. Rev. D 79, 111101(R) – Published 5 June 2009

Abstract

Using data acquired with the CLEO-c detector at the CESR $e^{+} e^{-}$ collider, we measure branching fractions for $J / ψ$ , $ψ (2 S)$ , and $ψ (3770)$ decays to $γ π^{0}$ , $γ η$ , and $γ η^{'}$ . Defining $R_{n} \equiv B [ψ (n S) \to γ η] / B [ψ (n S) \to γ η^{'}]$ , we obtain $R_{1} = (21.1 \pm 0.9) %$ and, unexpectedly, an order of magnitude smaller limit, $R_{2} < 1.8 %$ at 90% C.L. We also use $J / ψ \to γ η^{'}$ events to determine branching fractions of improved precision for the five most copious $η^{'}$ decay modes.