To validate the molecular description of the observed Z b (10610)/Z b (10650) and Z c (3900)/Z c (4025), it is valuable to investigate their counterparts, denoted as Z (′) QV in this work, and the corresponding decay modes. In this work, we present an analysis of the Z (′) QV using flavor symmetry. We also use the effective Lagrangian based on the heavy quark symmetry to explore the rescattering mechanism and calculate the partial widths for the isospin conserved channels Z (′) QV → η Q V . The predicted partial widths are of an order of MeV for Z QV → η Q V , which correspond to branching ratios of the order of 10 −2 ∼ 10 −1 .For Z ′ QV → η Q V , the partial widths are a few hundreds of keV and the branching ratios are about 10 −3 . Future experimental measurements can test our predictions on the partial widths and thus examine the molecule description of heavy quarkoniumlike exotic states.

We identify open charm effects in a direct production process e + e − → J/ψπ 0 . A unique feature of this process is that the DD * + c.c. threshold is located at a relatively isolated energy region, i.e. ∼ 3.876 GeV, which is far away from the well-established charmonia ψ(3770) and ψ(4040). Therefore, the cross section line-shape of this reaction provides an opportunity for singling out the open charm effects. A model-independent narrow enhancement between the thresholds of D 0D * 0 + c.c. and D + D * − + c.c. is predicted. This study can also help understand the X(3900) enhancement recently observed by the Belle and BaBar Collaboration in e + e − → DD + c.c. We also show that the open charm effects play a crucial role for our understanding of the long-standing "ρπ puzzle"