(J/ψ, J/ψ), and (ηc, ηc) production through two intermediate photons in electron-positron annihilation at B-factories

We study the processes, e⁻ e⁺ → γ^* γ^* → J/ψ +J/ψ, and e⁻ e⁺ → γ^* γ^* → ηc+ ηc at √s=10.6 GeV in the framework of 4× 4 Bethe-Salpeter equation. For J/ψ+J/ψ production, the dominant contribution is through fragmentation process, while for ηc+ηc production, the quark rearrangement diagrams contribute. Our results of cross section for J/ψ+J/ψ and ψ(2S)+ψ(2S) are compatible with the experimental upper limits set by Belle Collaboration, while in the absence of experimental data for ηc(1S)+ηc(1S), and ηc(2S)+ηc(2S) production, we have given theoretical prediction of their cross sections, and compared with NRQCD prediction.