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

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

M. Ablikim et al. (BES Collaboration)

Phys. Rev. Lett. 101, 102004 – Published 5 September 2008

Abstract

We observe an obvious anomalous line shape of the $e^{+} e^{-} \to$ hadrons total cross sections in the energy region between 3.700 and 3.872 GeV. It is inconsistent with the explanation for only one simple $ψ (3770)$ resonance with a statistical significance of $7 σ$ . 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 and 3.779 GeV, indicating 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 $D \bar{D}$ production dynamics.