$D^{\ast }{\bar{D}}^{\ast }$ molecule interpretation of $Z_c(4025)$

Abstract

We have used QCD sum rules to study the newly observed charged state $Z_c(4025)$ as a hidden-charm $D^{\ast }{\bar{D}}^{\ast }$ molecular state with the quantum numbers $I^G(J^P)=1^{+}(1^{+})$. Using a $D^{\ast }{\bar{D}}^{\ast }$ molecular interpolating current, we have calculated the two-point correlation function and the spectral density up to dimension eight at leading order in ${\alpha }_s$. The extracted mass is $m_X=(4.04\pm 0.24)$ GeV. This result is compatible with the observed mass of $Z_c(4025)$ within the errors, which implies a possible molecule interpretation of this new resonance. We also predict the mass of the corresponding hidden-bottom $B^{\ast }{\bar{B}}^{\ast }$ molecular state: $m_{Z_b}=(9.98\pm 0.21)$ GeV.

Comments: 6 pages, 5 figures. Version appears in Eur. Phys. J. C