Measurements ofJ/ψdecays into a vector and a pseudoscalar meson

We present measurements of the two-body decays of the J/{ψ} into a vector and a pseudoscalar meson. The data, taken with the Mark III detector at the SLAC e⁺{e}^{{{-}}}storage ring SPEAR, consist of 5.8×{10}⁶$ produced J/{ψ}'s. The branching ratios for the J/{ψ} decays into {ρ}{π}, {ρ}{η}, {ρ}{η}', {ω}π⁰, {ω}{η}, {ω}{η}', {φ}{η}, {φ}{η}', and K*K are measured; an upper limit on J/{ψ}{→}{φ}π⁰ is obtained. Using the measured branching ratios we obtain parameters of a phenomenological model of J/{ψ} decays, indicating that the {η} and {η}' are consistent with being composed only of light and strange quarks. The model is used to obtain the mixing angle in the pseudoscalar nonet. The {ω}π⁰ electromagnetic form factor is determined. The upper limit on J/{ψ}{→}{φ}π⁰ is used to study the contributions from electromagnetic doubly--Okubo-Zweig-Iizuka--suppressed decays of the J/{ψ}. .AE