Mass spectra of four-quark states in the hidden charm sector
Abstract.Masses of the low-lying four-quark states in the hidden charm sector ( $ cq\bar{c}\bar{q}; q\in u,d$ are calculated within the framework of a non-relativistic quark model. The four-body system is considered as two two-body systems such as diquark-antidiquark ( $ Qq$ - $ \bar{Q}$$ \bar{q}$ and quark-antiquark-quark-antiquark ( $ Q\bar{q}$ -$ \bar{Q}$q molecular-like four-quark states. Here, the Cornell-type potential has been used for describing the two-body interactions among Q -q , $ \bar{Q}$ -$ \bar{q}$ , Q -$ \bar{q}$ , Qq - $ \bar{Q}\bar{q}$ and Q$ \bar{q}$ -$ \bar{Q}$q , with appropriate string tensions. Our present analysis suggests the following exotic states: X(3823) , Zc(3900) , X(3915) , Zc(4025) , $ \psi$(4040) , Z1(4050) and X(4160) as Q$ \bar{q}$ -$ \bar{Q}$q molecular-like four-quark states, while Zc(3885) , X(3940) and Y(4140) as the diquark-antidiquark four-quark states. We have been able to assign the JPC values for many of the recently observed exotic states according to their structure. Apart from this, we have identified the charged state Z(4430) recently confirmed by LHCb as the first radial excitation of Zc(3885) with G = + 1 and Y(4360) state as the first radial excitation of Y(4008) with G = - 1 and the state $ \psi(4415)$ as the first radial excitation of the $ \psi(4040)$ state.