Gluonic mesons in $J/\psi$ radiative decay

Abstract

Two–gluon coupling of gluonic mesons is estimated in a spectator model to be considerably larger than that of $Q\bar{Q}$ . As an example of a gluonic meson that may be produced in $J/\psi$ radiative decay, we analyse $\eta(1760)$ . We deduce from experimental data that its branching ratio to two gluons is bounded, $0.4\pm 0.3 \stackrel{<}{\scriptstyle \sim} BR(\eta(1760)\rightarrow gg)\stackrel{<}{\scriptstyle \sim} 0.9\pm 0.3$ , consistent with a gluonic meson, but not compelling it. We propose further tests, and estimate the two–photon coupling of $\eta(1760)$ to be $1.4\pm 0.7$ keV.