Reanalysis of the Z c (4020), Z c (4025), Z(4050) and Z(4250) as Tetraquark States with QCD Sum Rules* *Supported by National Natural Science Foundation of Chian under Grant No. 11375063, and Natural Science Foundation of Hebei Province under Grant No. A2014502017

Abstract

In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the Cγμ — Cγν 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 favor assigning the Zc(4020) and Zc(4025) as the JPC = 1+− or 2++ diquark-antidiquark type tetraquark states, while the prediction disfavors assigning the Z(4050) and Z(4250) as the JPC = 0++ diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0++, 1+−, 2++ diquark-antidiquark type tetraquark states in details.