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As a test of the color-singlet mechanism of the nonrelativistic QCD (NRQCD)factorization approach, we consider the exclusive two-quarkonium productions inelectron-positron annihilation e+ e- -> eta_c + gamma and e+ e- -> J/psi +J/psi at B factories. The cross sections are computed to the next-to-leadingorder in alpha_s and are resummed to all orders in half the relative velocity vof the charm quark in each meson rest frame. The available theoreticalprediction of the cross section for e+ e- -> J/psi + eta_c at the same level oftheoretical accuracies is consistent with the available experimental data.Those for e+ e- -> eta_c + gamma and e+ e- -> J/psi + J/psi that are computednew in this work can be tested against the data from future super B factories.

Higher-order corrections to exclusive production of charmonia at B factories