Measurement of $e^{+}{e}^{-}\to \ddot{I}{€}^0\ddot{I}{€}^0\ddot{I}ˆ(3686)$ at $\sqrt{s}$ from 4.009 to 4.600 GeV and observation of a neutral charmoniumlike structure

Abstract

Using $e^{+}{e}^{-}$ collision data collected with the BESIII detector at the BEPCII collider corresponding to an integrated luminosity of 5.2 $f{b}^{-1}$ at center-of-mass energies ($\sqrt{s}$) from 4.009 to 4.600 GeV, the process $e^{+}{e}^{-}\to \ddot{I}{€}^0\ddot{I}{€}^0\ddot{I}ˆ(3686)$ is studied for the first time. The corresponding Born cross sections are measured and found to be half of those of the reaction $e^{+}{e}^{-}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}ˆ(3686)$. This is consistent with the expectation from isospin symmetry. Furthermore, the Dalitz plots for $\ddot{I}{€}^0\ddot{I}{€}^0\ddot{I}ˆ(3686)$ are accordant with those of $\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}ˆ(3686)$ at all energy points, and a neutral analogue to the structure in $\ddot{I}{€}^{\pm }\ddot{I}ˆ(3686)$ around 4040 MeV/$c^2$ first observed at $\sqrt{s}$=4.416 GeV is observed in the isospin neutral mode at the same energy.