Measurements of the line shapes of DD¯ production and the ratio of the production rates of D+D−D+D− and D0D¯0 in e+e−e+e− annihilation at ψ(3770)ψ(3770) resonance

We report measurements of the line shapes of D+D−D+D−, D0D¯0 and DD¯ production as well as the line shape of the ratio of the production rates of D+D−D+D− and D0D¯0 in e+e−e+e− annihilation at ψ(3770)ψ(3770) resonance. We find that the line shapes of D+D−D+D−, D0D¯0 and DD¯ production are similar to an anomalous line shape of cross sections for e+e−→hadronse+e−→hadrons observed in the center-of-mass energy range from 3.70 to 3.87 GeV.