Radiative decays of charmonium into light mesons

Abstract

We apply perturbative QCD to the radiative decays of charmonia $J/\psi$ and ${\chi }_{cJ}$ into light mesons. We perform a complete numerical calculation for the quark-gluon loop diagrams involved in these processes. The calculated $J/\psi$ decay branching ratios to P-wave mesons $f_2(1270)$ and $f_1(1285)$ fit the data well, while that of $f_0(980)$ (if treated as an $s\bar{s}$ meson) is predicted to be $1.6\times 10^{-4}$, which implies that $f_0(1710)$ can not be the $s\bar{s}$ or $(u\bar{u}+d\bar{d})/\sqrt{2}$ meson. Decays of P-wave charmonia ${\chi }_{cJ}\to \rho (\omega ,\varphi )\gamma$ (J=0,1,2) are also studied, and the branching ratio of ${\chi }_{c1}\to \rho \gamma$ is predicted to be $1.4\times 10^{-5}$, which may be tested by CLEO-c and BESIII with future experiments.

Comments: journal version; a note on the f_2(1270) helicity added