Search for the decay $\ddot{I}{‡}_{c1}(3872)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{‡}_{c1}$

Abstract

Using a data sample corresponding to an integrated luminosity of 10.9 fb${}^{-1}$ collected at center-of-mass energies from 4.16 to 4.34 GeV with the BESIII detector, we search for the decay $\ddot{I}{‡}_{c1}(3872)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{‡}_{c1}$ in the radiative production $e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c1}(3872)$. No significant signal is observed, and the ratio for the branching fraction of $\ddot{I}{‡}_{c1}(3872)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{‡}_{c1}$ to $\ddot{I}{‡}_{c1}(3872)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}J/\ddot{I}ˆ$ is measured as $\mathcal{R}\equiv \frac{\mathcal{B}[\ddot{I}{‡}_{c1}(3872)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{‡}_{c1}]}{\mathcal{B}[\ddot{I}{‡}_{c1}(3872)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}J/\ddot{I}ˆ]}<0.18$ at 90$\%$ confidence level. The upper limit on the product of the cross section $\ddot{I}ƒ[e^{+}{e}^{-}\to {\hat{I}}^3\ddot{I}{‡}_{c1}(3872)]$ and the branching fraction $\mathcal{B}[\ddot{I}{‡}_{c1}(3872)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{‡}_{c1}]$ at each center-of-mass energy is also given. These measurements favor the non-conventional charmonium nature of the $\ddot{I}{‡}_{c1}(3872)$ state.

8 pages, 1 figure