Reanalysis of exclusive charmonium production at the $B$ factories

In this paper, we present a comprehensive analysis of the next-to-next-to-leading-order (NNLO) QCD corrections to the exclusive processes $e^{+}e^{-}\to J/ψ+η_{c}$, $e^{+}e^{-}\to J/ψ+χ_{cJ}$, $e^{+}e^{-}\to η_{c}+γ$, and $e^{+}e^{-}\to χ_{cJ}+γ$ $(J=0,1,2)$ at the $B$ factories, comparing perturbat