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

In this article, we take the Y (4260/4220) as the vector tetraquark state with J(PC) = 1(--), and construct the C gamma 5 circle times (partial derivative) over left right arrow (mu) circle times gamma 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 C gamma 5 circle times (partial derivative) over left right arrow (mu) circle times gamma 5C type vector tetraquark state, and disfavors assigning the Z(c)(4100) to be the C gamma 5 circle times (partial derivative) over left right arrow (mu) circle times gamma 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.