Factorization and next-to-leading-order QCD correction in e+e-→J/ψ(ψ(2S))+χc0

In nonrelativistic QCD, we study e+e-→J/ψ(ψ(2S))+χc0 at B factories, where the P-wave state χc0 is associated with a S-wave state J/ψ or ψ(2S). In contrast to the failure of factorization in most cases involving P-wave states, e.g. in B decays, we find that factorization holds in this process at next-to-leading order (NLO) in αs and leading order in v, where the associated S-wave state plays a crucial rule in canceling the infrared divergences. We also give some general analyses for factorization in various double charmonium production. The NLO corrections in e+e-→J/ψ(ψ(2S))+χc0 at √(s)=10.6 GeV are found to substantially enhance the cross sections by a factor of about 2.8; hence crucially reducing the large discrepancy between theory and experiment. With mc=1.5 GeV and μ=2mc, the NLO cross sections are estimated to be 17.9(11.3) fb for e+e-→J/ψ(ψ(2S))+χc0, which reach the lower bounds of the experiment.