The continuum and interference effect in $e^+e^-\to D^0\bar{D}^0, D^+D^-$ processes

In the $e^+e^-$ annihilation processes $e^+e^-\to D^0\bar{D}^0, D^+D^-$ near or above the threshold of $D\bar{D}$, there are not only the resonance contribution $e^+e^-\to \psi (3770)\to D^0\bar{D}^0, D^+D^-$, but also the continuum contribution through virtual photon directly $e^+e^-\to \gamma^*\to D^0\bar{D}^0, D^+D^-$. The amplitudes through virtual photon directly and through resonance can interfere seriously. We consider the continuum and interference effect in the $D\bar{D}$ production process in $e^+e^-$ annihilation. We find that the effect is significant near and above the threshold of the $D\bar{D}$ mesons.