Understanding the e⁺e^- → D ^{(*) +}D^{(*) -} Processes observed by Belle

We calculate the production cross sections for D* ⁺D*^-, D⁺D*^- and D⁺D^- in e⁺e^- annihilation through one virtual photon in the framework of perturbative QCD with constituent quarks. The calculated cross sections for D*⁺D*^- and D⁺D*^- production are roughly in agreement with the recent Belle data. The helicity decomposition for D* meson production is also calculated. The fraction of the D*^± _LD*^∓_T final state in the e ⁺e^- → D*⁺D*^- process is found to be 65%. The fraction of DD*_T production is 100% and DD*_L is forbidden in e⁺e^- annihilation through one virtual photon. We further consider e⁺e ^- annihilation through two virtual photons, and then find the fraction of DD*_T in the e⁺e^- → DD* process to be about 91%.