Could Z_(c)(3900) be a I^(G)J^(P)=1⁺1⁺ D^(*)bar{D} molecular state?

We investigate the nature of the recently observed narrow resonance $Z_{c}(3900)$, which is assumed to be a $D^{*}\bar{D}$ molecular state with quantum numbers $I^{G}J^{P}=1^{+}1^{+}$. Using QCD sum rules, we consider contributions up to dimension eight in the operator product expansion and work at the leading order in $\alpha_{s}$. The mass we arrived at is $(3.88 \pm 0.17) \mbox{GeV}$, which coincides with the mass of $Z_{c}(3900)$.