Recently, the BESIII Collaboration reported a new measurement of the $\eta_c \rho$ decay mode of $Z_c^{ (\prime)}$, which motivated us to study the inner structure of $Z_c^{ (\prime)}$ via investigating the hidden charm decays of these two $Z_c$ states. We consider the { triangle loop mechanism} contribution in the hidden charm decays of $Z_c^{ (\prime)}$. Our estimations indicate that the triangle loop mechanism plays an important role in the decays of the $Z_c^{ (\prime)}$, where our results are in agreement with the experimental observations in a reasonable parameter range. Furthermore, we point out that the $Z_c^{ (\prime)}$ can be interpreted as the hadronic molecules, while the tetraquark scenario is less favored.
Categories: hep-ph