Exploratory study of the coupled-channel scattering in finite volume and the $Z_c(3900)$ resonance

In this note we first introduce the theoretical formalism of the unitarization of the two-body scattering both in the infinite and finite volumes. Then we apply this formalism to the study of the $Z_c(3900)$ resonance in the $J\mathrm{/}\psi \pi$ and $D{\bar{D}}^{\ast }$ coupled-channel scattering. The recent lattice finite-volume spectra are confronted with our predictions.