J/ψdecays into a vector and a pseudoscalar meson and the quark content of theηand η’

From a study of 2.7×${10}^6$ J/ψ decays with the Mark III detector at the SLAC storage ring SPEAR, we have obtained new measurements of the two-body decays of the J/ψ into a vector and a pseudoscalar meson. We present branching ratios for decays to ρπ, ${\mathrm{KK}}^{\mathrm{*}}$(892), φη, the previously unobserved modes φη’, ωη, ωη’, ω${\pi }^0$, ${\rho }^0$η, and new upper limits on ${\rho }^0$η’ and φ${\pi }^0$. In the decay J/ψ→η${\pi }^{+}$ ${\pi }^{\mathrm{-}}$, we observe ${\rho }^0$-ω interference. The collection of measured branching ratios are simultaneously fit to a simple model of J/ψ decays which includes strong and electromagnetic amplitudes and allows for violation of SU(3) invariance. Using this model, we calculate the strange- and nonstrange-quark content of the η and η’ and conclude that (35±18)% of the η’ wave function can be attributed to an additional component, e.g., gluonium or radial excitation. The measurement of the ω${\pi }^0$ branching ratio, when combined with that of the γ${\pi }^0$ decay mode of the ω, yields a determination of the ω${\pi }^0$ electromagnetic-form-factor ratio ‖f($q^2$=$m_{J/\psi }$ ${\mathrm{}}^2$)/f($q^2$=0) ‖=0.038±0.006.