The cross section of the process e+ + e- → J/ψ + ηc within the QCD light-cone sum rules

We calculate the cross section of the exclusive process e(+) + e(-) -> J/psi + eta(c) at the leading order approximation within the QCD light-cone sum rules approach. It is found that the form factor F-VP(V = J/psi, P = eta(c)) depends mainly on the behavior of the twist-2 distribution amplitude of the eta(c) meson at the scale of this process. Thus in order to obtain a reliable estimation of the cross section, it is important to have a realistic distribution amplitude of the eta(c) meson and to deal with the evolution of the distribution amplitude to the effective energy scale of the process. Our results show that one can obtain a compatible prediction with the Belle and BaBar experimental data.