Reanalysis of the Z c(4020), Z c(4025), Z(4050) and Z(4250) as Tetraquark States with QCD Sum Rules*

In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the Cγ μ — Cγ ν type scalar, axial-vector and tensor tetraquark states in details with the QCD sum rules. In calculations, we use the formula to determine the energy scales of the QCD spectral densities. The predictions M J = 2 = ( 4.02 - 0.09 + 0.09 ) GeV , M J = 1 = ( 4.02 - 0.08 + 0.07 ) GeV favor assigning the Z c (4020) and Z c (4025) as the J PC = 1 +− or 2 ++ diquark-antidiquark type tetraquark states, while the prediction M J = 0 = ( 3.85 - 0.09 + 0.15 ) GeV disfavors assigning the Z(4050) and Z(4250) as the J PC = 0 ++ diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0 ++ , 1 +− , 2 ++ diquark-antidiquark type tetraquark states in details.