Anomalous Line-Shape of Cross Sections for $e^{+}{e}^{-}\to \mathrm{Hadrons}$ in the Center-of-Mass Energy Region between 3.650 and 3.872 GeV

Abstract

We observe an obvious anomalous line-shape of the $e^{+}{e}^{-}\to \mathrm{hadrons}$ total cross sections in the energy region between 3.700 and 3.872 GeV from the data samples taken with the BES-II detector at the BEPC Collider. Re-analysis of the data shows that it is inconsistent with the explanation for only one simple $\ddot{I}ˆ(3770)$ resonance with a statistical significance of $7\ddot{I}ƒ$. The anomalous line-shape may be explained by two possible enhancements of the inclusive hadron production near the center-of-mass energies of 3.764 GeV and 3.779 GeV, indicating that either there is likely a new structure in addition to the $\ddot{I}ˆ(3770)$ resonance around 3.773 GeV, or there are some physics effects reflecting the $D\bar{D}$ production dynamics.

6 pages, 3figures