Resummation of relativistic corrections to exclusive productions of charmonia in e(+)e(-) collisions

Abstract

We investigate two exclusive processes, e(+)e(-) -> eta(c) + gamma and e(+)e(-) -> J/psi + J/psi, at the center-of-momentum energy root s = 10.58 GeV within the framework of the nonrelativistic QCD factorization approach. A class of relativistic corrections is resummed to all orders in the heavy-quark velocity v and the corrections are large negative. We further improve the prediction by including available QCD next-to-leading-order corrections and the interference between the QCD and relativistic corrections. The prediction for sigma[e(+)e(-) -> eta(c) + gamma] is about 50 fb. In the case of e(+)e(-) -> J/psi + J/psi the standard nonrelativistic QCD prediction for the cross section is negative. As an alternative, the vector-meson-dominance approach is employed to compute the photon-fragmentation contribution of the process, which gives the cross section similar to 1 fb. This is an indication that the uncalculated QCD higher-order corrections may be significant. Our results can be tested against the forthcoming data from Belle II and super B factories.