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

Abstract

Abstract In this work, we study the $$D\bar{D}$$ D D ¯ , DD, $$D\bar{D}_s$$ D D ¯ s , $$DD_s$$ D D s , $$D_s\bar{D}_s$$ D s D ¯ s and $$D_sD_s$$ D s D s tetraquark molecular states with the $$J^{PC}=0^{++}$$ J PC = 0 + + via the QCD sum rules. The prediction $$M_{D_s\bar{D}_s} = 3.98\pm 0.10\, \text {GeV}$$ M D s D ¯ s = 3.98 ± 0.10 GeV is in very good agreement with the experimental value $$M_{X(3960)} = 3956 \pm 5\pm 10 \,\text {MeV}$$ M X ( 3960 ) = 3956 ± 5 ± 10 MeV from the LHCb collaboration and supports assigning the X(3960) as the $$D_s^+D_s^-$$ D s + D s - molecular state with the $$J^{PC}=0^{++}$$ 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.