Inclusive production of four charm hadrons in e⁺e^- annihilation at B factories

Measurements by the Belle Collaboration of the exclusive production of two charmonia in e⁺e^- annihilation differ substantially from theoretical predictions. Till now, no conclusive explanation for this remarkable discrepancy has been provided. Even the origin of the discrepancy is not identified, yet. We suggest that the measurement of four-charm events in Belle data must provide a strong constraint in identifying the origin of this large discrepancy. Our prediction of the cross section for e⁺e^- → cc̄cc̄, in lowest order in strong coupling constant, at √s = 10.6 GeV is about 0.1 pb. If measured four-charm cross section is compatible with the prediction based on perturbative QCD, it is very likely that factorization of the hadronization process from perturbative part may be significantly violated or there exists a new production mechanism. If the cross section for the four-charm event is also larger than the prediction like that for the exclusive J/ψ + η_c production, perturbative QCD expansion itself will be proved to be unreliable and loses predictive power.