Study of $\ensuremath{\psi}(2S)$ decays to $\ensuremath{\gamma}p\overline{p}$, ${\ensuremath{\pi}}^{0}p\overline{p}$, and $\ensuremath{\eta}p\overline{p}$, and search for $p\overline{p}$ threshold enhancements

Study of $ψ (2 S)$ decays to $γ p \bar{p}$ , $π^{0} p \bar{p}$ , and $η p \bar{p}$ , and search for $p \bar{p}$ threshold enhancements

J. P. Alexander et al. (CLEO Collaboration)

Phys. Rev. D 82, 092002 – Published 5 November 2010

Abstract

The decays of $ψ (2 S)$ into $γ p \bar{p}$ , $π^{0} p \bar{p}$ , and $η p \bar{p}$ have been studied with the CLEO-c detector using a sample of $24.5 \times 10^{6}$ $ψ (2 S)$ events obtained from $e^{+} e^{-}$ annihilations at $\sqrt{s} = 3686 MeV$ . The data show evidence for the excitation of several $N^{*}$ resonances in $p π^{0}$ and $p η$ channels in $π^{0} p \bar{p}$ and $η p \bar{p}$ decays, and $f_{2}$ states in $γ p \bar{p}$ decay. Branching fractions for decays of $ψ (2 S)$ to $γ p \bar{p}$ , $π^{0} p \bar{p}$ , and $η p \bar{p}$ have been determined. No evidence for $p \bar{p}$ threshold enhancements was found in the reactions $ψ (2 S) \to X p \bar{p}$ , where $X = γ$ , $π^{0}$ , $η$ . We do, however, find confirming evidence for a $p \bar{p}$ threshold enhancement in $J / ψ \to γ p \bar{p}$ as previously reported by BES.