Zc(3900)/Zc(3885) as a virtual state from π J/ψ - (D)over-bar* D interaction

In this work, we study the pi J/psi and (D) over bar* D invariant mass spectra of the Y (4260) decay to find out the origin of the Z(c)(3900) and Z(c)(3885) structures. The pi J/psi - (D) over bar* D interaction is studied in a coupled - channel quasi-potential Bethe - Saltpeter equation approach, and embedded to the Y (4260) decay process to reproduce both pi(-)J/psi and D*-D-0 invariant mass spectra observed at BESIII simultaneously. It is found out that a virtual state at energy about 3870 MeV is produced from the interaction when both invariant mass spectra are comparable with the experiment. The results support that both Z(c)(3900) and Z(c)(3885) have the same origin, that is, a virtual state from pi J/psi (D) over bar* D interaction, in which the (D) over bar* D interaction is more important and the coupling between (D) over bar* D and pi J/psi channels plays a minor role.