We have studied the loosely bound $D^*\bar{ D}^*$ system. Our results indicate that the recently observed charged charmonium-like structure $Z_c(4025)$ can be an ideal $D^*\bar{ D}^*$ molecular state. We have also investigated its pionic, dipionic, and radiative decays. We stress that both the scalar isovector molecular partner $Z_{ c0}$ and three isoscalar partners ${ \tilde Z}_{ c0,c1,c2}$ should also exist if $Z_c(4025)$ is a $D^*\bar{ D}^*$ molecular state { in the framework of the one-pion-exchange model}. $Z_{ c0}$ can be searched for in the channel $e^+e^-\to Y \to Z_{ c0}(4025)\left(\pi\pi\right)_{ P-wave}$ where $Y$ can be Y(4260) or any other excited $1^{ --}$ charmonium or charmonium-like states such as Y(4360), Y(4660) etc. The isoscalar $D^*\bar{ D}^*$ molecular states ${ \tilde Z}_{ c0,c2}$ with $0^+(0^{ ++})$ and $0^+(2^{ ++})$ can be searched for in the three pion decay channel $e^+e^-\to Y \to { \tilde Z}_{ c0,c2} \left(3\pi\right)^{ I=0}_{ P-wave}$. The isoscalar molecular state ${ \tilde Z}_{ c1}$ with $0^-(1^{ +-})$ can be searched for in the channel ${ \tilde Z}_{ c1}\eta$. Experimental discovery of these partner states will firmly establish the molecular picture.
Categories: hep-ph hep-ex