Analysis of the X(3960) and related tetraquark molecular states via the QCD sum rules

In this work, we study the \(D\bar{D}\), DD, \(D\bar{D}_s\), \(DD_s\), \(D_s\bar{D}_s\) and \(D_sD_s\) tetraquark molecular states with the \(J^{PC}=0^{++}\) via the QCD sum rules. The prediction \(M_{D_s\bar{D}_s} = 3.98\pm 0.10\, \text {GeV}\) is in very good agreement with the experimental value \(M_{X(3960)} = 3956 \pm 5\pm 10 \,\text {MeV}\) from the LHCb collaboration and supports assigning the X(3960) as the \(D_s^+D_s^-\) molecular state with the \(J^{PC}=0^{++}\). We take account of our previous works on the four-quark states consisting of two color-neutral clusters and acquire the mass spectrum of the ground state hidden-charm and doubly-charm tetraquark molecular states.