The BESIII collaboration reported an observation of two charged charmonium-like structure $Z_c^{ \pm}(3900)$ and $Z_c^{ \pm}(4025)$ in $e^+e^- \to (J/\psi \pi)^{ \pm} \pi^{ \mp}$ and $e^+e^- \to (D^* { \bar D}^*)^{ \pm} \pi^{ \mp}$ at ${ \sqrt s} =4.26$ GeV recently, which could be an analogue of $Z_b(10610)$ and $Z_b(10650)$ claimed by the Belle Collaboration. In this work, we investigate the hidden-charmonium transitions of $Z_c^{ \pm}(3900)$ and $Z_c^{ \pm}(4025)$ via intermediate $D^{ (*)} { D}^{ (*)}$ meson loops. Reasonable results for the branching ratios by taking appropriate values of $\alpha$ in this model can be obtained, which shows that the intermediate $D^{ (*)} { D}^{ (*)}$ meson loops process may be a possible mechanism in these decays. Our results are consistent with the power-counting analysis, and comparable with the calculations in the framework of nonrelativistic effective field theory to some extent. We expect more experimental measurements on these hidden-charmonium decays and search for the decays of $Z_c\to D{ \bar D}^* +c.c.$ and $Z_c^\prime \to D^* { \bar D}^*$, which will help us investigate the $Z_c^{ (\prime)}$ decays deeply.
Categories: hep-ph