Vector tetraquark state candidates: Y(4260 / 4220), Y(4360 / 4320), Y(4390) and Y(4660 / 4630)

In this article, we construct the C ⊗ γ μ C and C γ 5 ⊗ γ 5 γ μ C type currents to interpolate the vector tetraquark states, then carry out the operator product expansion up to the vacuum condensates of dimension-10 in a consistent way, and obtain four QCD sum rules. In calculations, we use the formula μ = M Y 2 - ( 2 M c ) 2 to determine the optimal energy scales of the QCD spectral densities, moreover, we take the experimental values of the masses of the Y (4260 / 4220), Y (4360 / 4320), Y (4390) and Y (4660 / 4630) as input parameters and fit the pole residues to reproduce the correlation functions at the QCD side. The numerical results support assigning the Y (4660 / 4630) to be the C ⊗ γ μ C type vector tetraquark state c c ¯ s s ¯ , assigning the Y (4360 / 4320) to be C γ 5 ⊗ γ 5 γ μ C type vector tetraquark state c c ¯ q q ¯ , and disfavor assigning the Y (4260 / 4220) and Y (4390) to be the pure vector tetraquark states.