Exclusive production of $J/\psi +{\eta }_c$ at the $B$ factories Belle and Babar using the principle of maximum conformality

Zhan Sun, Xing-Gang Wu, Yang Ma +1

We predict the rate for exclusive double-charmonium production in electron-positron annihilation $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ using perturbative quantum chromodynamics and the NRQCD frame…