Observation of Anomalous Line Shape of ψ(3770) Production and Measurements of Branching Fractions for J∕ψ, ψ(3686) and ψ(3770)→K[sup 0]∕K[sup ∗0]X

We observe an obviously anomalous line shape of the cross sections for e+e−→ hadrons and e+e−→DD̄ in the energy region between 3.700 and 3.872 GeV. They are inconsistent with the explanation for only one simple ψ(3770) resonance in the range from 3.70 to 3.87 GeV, which indicates that either there is likely a new structure in addition to the ψ(3770) resonance around 3.773 GeV, or there are some physics effects reflecting the DD̄ production dynamics. With the data taken around 3.097, 3.686 and 3.770 GeV, we measure the inclusive K0/K*0 decay branching fractions of the J/ψ, ψ(3686) and ψ(3770) resonances for the first time.