Measurement of the $e^{+}{e}^{-}\to \ddot{I}‰\ddot{I}{€}^0\ddot{I}{€}^0$ cross section at center-of-mass energies from 2.0 to 3.08 GeV

Abstract

The cross section of the process $e^{+}{e}^{-}\to \ddot{I}‰\ddot{I}{€}^0\ddot{I}{€}^0$ is measured at nineteen center-of-mass energies from 2.0 to 3.08 GeV using data collected with the BESIII detector at the BEPCII storage ring. A resonant structure around 2.20 GeV is observed with statistical significance larger than $5\ddot{I}ƒ$. Using a coherent fit to the cross section line shape, the mass and width are determined to be $M=2222\pm 7\pm 2\mathrm{MeV}/c^2$ and $\Gamma =59\pm 30\pm 6\mathrm{MeV}$, respectively, where the first uncertainties are statistical and the second ones are systematic.