Figure 1

Differential cross sections $d\sigma /d|x|$ for $e^{+}{e}^{-}$ annihilation into $J/\psi +J/\psi$ and $J/\psi +{\eta }_c$ at $E_{\mathrm{beam}}=5.3\mathrm{GeV}$. The areas under the curves are the integrated cross sections 6.65 and 3.78 fb. There are large errors associated with QCD and relativistic corrections, as described in the text.Reuse & Permissions