Could $Z_c(3900)$ be a $I^G{J}^P=1^{+}{1}^{+}$ $D^{\ast }\bar{D}$ molecular state?

Abstract

We investigate the nature of the recently observed narrow resonance $Z_c(3900)$, which is assumed to be a $D^{\ast }\bar{D}$ 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 $(3.88\pm 0.17)\text{mbox}GeV$, which coincides with the mass of $Z_c(3900)$.

Comments: 8 pages, 5 figures. accepted by JPG. arXiv admin note: substantial text overlap with arXiv:1107.1343