Lowest vector tetraquark states: Y(4260 / 4220) or Zc(4100) Z c ( 4100 )

In this article, we take the Y(4260 / 4220) as the vector tetraquark state with JPC=1⁻⁻ , and construct the Cγ ₅⊗ ∂ ↔_μ ⊗ γ ₅C type diquark-antidiquark current to study its mass and pole residue with the QCD sum rules in details by taking into account the vacuum condensates up to dimension 10 in a consistent way. The predicted mass MY=4.24± 0.10\,GeV is in excellent agreement with experimental data and supports assigning the Y(4260 / 4220) to be the Cγ ₅⊗ ∂ ↔_μ ⊗ γ ₅C type vector tetraquark state, and disfavors assigning the Zc(4100) to be the Cγ ₅⊗ ∂ ↔_μ ⊗ γ ₅C type vector tetraquark state. It is the first time that the QCD sum rules have reproduced the mass of the Y(4260 / 4220) as a vector tetraquark state.