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Motivated by the experimental study of $J/\psi\to\gamma ~+$ invisible decayby the CLEO Collaboration, we analyze the process $J/\psi\to \gamma\nu\bar{\nu}$, as the standard model background for this invisible decay, atthe lowest order. Our investigation shows that Br($J/\psi\to \gamma\nu\bar{\nu}$) is far below the present experimental upper limit on thebranching ratio of $J/\psi\to\gamma ~+$ invisible, which indicates that someinteresting room for new physics in this channel might be expected. We alsopresent a similar analysis of the $\eta_c\to \gamma \nu\bar{\nu}$ decay.

Analysis of $J/\psi(\eta_c)\to \gamma ~+$ invisible decays in the standard model