New approach to finding invisible states in $e^{+}{e}^{-}$ annihilation and application to BESIII data

Glennys R. Farrar, Qi-Ming Li, Chang-Zheng Yuan

We compare precision $e^{+}{e}^{-}$ to ${\mu }^{+}{\mu }^{-}$ cross section measurements by BESIII in the E_cm =3.8-4.6 GeV range, to predictions based on measured R_had data. The consistency is poor…