Observation of $e^{+}{e}^{-}\to \hat{I}\cdot J/\ddot{I}ˆ$ at center-of-mass energy $sqrts=4.009$ GeV

Abstract

Using a 478 pb${}^{-1}$ data sample collected with the BESIII detector operating at the BEPCII storage ring at a center-of-mass energy of $\sqrt{s}=4.009$ GeV, the production of $e^{+}{e}^{-}\to \hat{I}\cdot J\ddot{I}ˆ$ is observed for the first time with a statistical significance of greater than $10\ddot{I}ƒ$. The Born cross section is measured to be $(32.1\pm 2.8\pm 1.3)$ pb, where the first error is statistical and the second systematic. Assuming the $\hat{I}\cdot J\ddot{I}ˆ$ signal is from a hadronic transition of the $\ddot{I}ˆ(4040)$, the fractional transition rate is determined to be $\mathcal{B}(\ddot{I}ˆ(4040)\to \hat{I}\cdot J\ddot{I}ˆ)=(5.2\pm 0.5\pm 0.2\pm 0.5)\times 10^{-3}$, where the first, second, and third errors are statistical, systematic, and the uncertainty from the $\ddot{I}ˆ(4040)$ resonant parameters, respectively. The production of $e^{+}{e}^{-}\to \ddot{I}{€}^{0}J\ddot{I}ˆ$ is searched for, but no significant signal is observed, and $\mathcal{B}(\ddot{I}ˆ(4040)\to \ddot{I}{€}^{0}J\ddot{I}ˆ)<2.8\times 10^{-4}$ is obtained at the 90% confidence level.

7 pages, 5 figures