Measurement of $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c0,c1,c2}$ cross sections at center-of-mass energies between 3.77 and 4.60 GeV

Abstract

The $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{cJ}$ ($J=0,1,2$) processes are studied at center-of-mass energies ranging from 3.773 to 4.600 GeV, using a total integrated luminosity of 19.3 fb${}^{-1}$ $e^{+}{e}^{-}$ annihilation data accumulated with the BESIII detector at BEPCII. We observe for the first time $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c1,c2}$ signals at $\sqrt{s}=$ 4.180 GeV with statistical significances of 7.6$\ddot{I}ƒ$ and 6.0$\ddot{I}ƒ$, respectively. The production cross section of $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c1,c2}$ at each center-of-mass energy is also measured. We find that the line shape of the $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c1}$ cross section can be described with conventional charmonium states $\ddot{I}ˆ(3686)$, $\ddot{I}ˆ(3770)$, $\ddot{I}ˆ(4040)$, $\ddot{I}ˆ(4160)$. Compared with this, for the $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c2}$ channel, one more additional resonance is added to describe the cross section line shape. Its mass and width are measured to be $M=4371.7\pm 7.5\pm 1.8$ MeV/$c^2$ and $\hat{I}{“}^{tot}=51.1\pm 17.6\pm 1.9$ MeV, where the first uncertainties are statistical and the second systematic. The significance of this resonance is estimated to be 5.8$\ddot{I}ƒ$, and its parameters agree with the $Y(4360)$ resonance previously reported in $e^{+}{e}^{-}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}ˆ(3686)$, and the $Y(4390)$ in $e^{+}{e}^{-}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}{h}_c$ within uncertainties. No significant signal for the $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c0}$ process is observed, and the upper limits of Born cross sections $\ddot{I}{ƒ}_B(e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c0})$ at 90\% confidence level are reported.

12 pages, 5 figures