Tetraquark state candidates: Y(4260), Y(4360), Y(4660), and Zc(4020/4025)

In this article, we construct the axialvector-diquark-axialvector-antidiquark type tensor current to interpolate both the vector-and the axialvector-tetraquark states, then calculate the contributions of the vacuum condensates up to dimension 10 in the operator product expansion, and we obtain the QCD sum rules for both the vector-and the axialvector-tetraquark states. The numerical results support assigning the Z(c)(4020/4025) to be the J(PC) = 1(+-) diquark-antidiquark type tetraquark state, and assigning the Y (4660) to be the J(PC) = 1(--) diquark-antidiquark type tetraquark state. Furthermore, we take the Y (4260) and Y (4360) as the mixed charmonium-tetraquark states, and we construct the two-quark-tetraquark type tensor currents to study the masses and pole residues. The numerical results support assigning the Y (4260) and Y (4360) to be the mixed charmonium-tetraquark states.