Observation of a Near-Threshold Enhancement in the $\ensuremath{\omega}\ensuremath{\phi}$ Mass Spectrum from the Doubly OZI-Suppressed Decay $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\omega}\ensuremath{\phi}$

Observation of a Near-Threshold Enhancement in the $ω ϕ$ Mass Spectrum from the Doubly OZI-Suppressed Decay $J / ψ \to γ ω ϕ$

M. Ablikim et al. (BES Collaboration)

Phys. Rev. Lett. 96, 162002 – Published 27 April 2006

Abstract

An enhancement near threshold is observed in the $ω ϕ$ invariant mass spectrum from the doubly Okubo-Zweig-Iizuka–suppressed decays of $J / ψ \to γ ω ϕ$ , based on a sample of $5.8 \times 10^{7}$ $J / ψ$ events collected with the BESII detector. A partial wave analysis shows that this enhancement favors $J^{P} = 0^{+}$ , and its mass and width are $M = 1812_{- 26}^{+ 19} (stat) \pm 18 (syst) MeV / c^{2}$ and $Γ = 105 \pm 20 (stat) \pm 28 (syst) MeV / c^{2}$ . The product branching fraction is determined to be $B (J / ψ \to γ X) B (X \to ω ϕ) = [2.61 \pm 0.27 (stat) \pm 0.65 (syst)] \times 10^{- 4}$ .