Observation of the decay $\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3$ at BESIII

Abstract

In the decays of $\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3$ and $J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}{\cdot }_c$, there are discrepancies between the theoretical calculations and the PDG experimental values, referred to as the charmonium QCD puzzle. We observe the decay $\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3$ in $J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}{\cdot }_c$ using $(2712.4\pm 14.3)\times 10^6$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector, and determine the product branching fraction $\mathcal{B}(J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}{\cdot }_c)\times \mathcal{B}(\hat{I}{\cdot }_c\to {\hat{I}}^3{\hat{I}}^3)=(5.23\pm 0.26_{stat.}\pm 0.30_{syst.})\times 10^{-6}$. This measurement is consistent with the two most recent lattice QCD calculations, providing significant input toward resolving the charmonium QCD puzzle.

Proceedings of The European Physical Society Conference on High Energy Physics (EPS-HEP2025), 7-11 July 2025, Marseille, France