A Study of J/psi-->gamma gamma V(rho,phi) Decays with the BESII Detector

Abstract

Using a sample of $58\times 10^6$ $J/ψ$ events collected with the BESII detector, radiative decays $J/ψ\toγγV$, where $V=ρ$ or $ϕ$, are studied. A resonance around 1420 MeV/c$^2$ (X(1424)) is observed in the $γρ$ mass spectrum. Its mass and width are measured to be $1424\pm 10(stat)\pm 11(sys)$ MeV/c$^2$ and $ 101.0\pm 8.8 \pm 8.8$ MeV/c$^2$, respectively, and its branching ratio $B(J/ψ\to γX(1424)\to γγρ)$ is determined to be $(1.07\pm0.17 \pm 0.11)\times 10^{-4}$. A search for $X(1424)\to γϕ$ yields a 95% C.L. upper limit $B(J/ψ\to γX(1424)\to γγϕ) < 0.82 \times 10^{-4}$.