Lowest vector tetraquark states: Y(4260\xa0/\xa04220) or Z_c(4100)

Zhi-Gang Wang

doi:10.1140/epjc/s10052-018-6417-5

Zhi-Gang Wang

Open Access

https://doi.org/10.1140/epjc/s10052-018-6417-5

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Abstract

In this article, we take the Y(4260 / 4220) as the vector tetraquark state with J^{PC}=1^{--}, and construct the Cgamma _5otimes {mathop {partial }limits ^{leftrightarrow }}_mu otimes 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 M_{Y}=4.24pm 0.10,mathrm {GeV} is in excellent agreement with experimental data and supports assigning the Y(4260 / 4220) to be the Cgamma _5otimes {mathop {partial }limits ^{leftrightarrow }}_mu otimes gamma _5C type vector tetraquark state, and disfavors assigning the Z_c(4100) to be the Cgamma _5otimes {mathop {partial }limits ^{leftrightarrow }}_mu otimes 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.

Highlights

In 2005, the BaBar collaboration observed the Y (4260) in the π +π − J/ψ mass spectrum in the initial-state radiation process e+e− → γI SRπ +π − J/ψ [1]
It is the first time that the QCD sum rules have reproduced the mass of the Y (4260/4220) as a vector tetraquark state
In 2014, the BES collaboration observed a resonance in the ωχc0 cross section in the processes e+e− → ωχc0/c1/c2, the measured mass and width are 4230 ± 8 ± 6 MeV and 38 ± 12 ± 2 MeV, respectively [24]

Summary

Introduction

In 2005, the BaBar collaboration observed the Y (4260) in the π +π − J/ψ mass spectrum in the initial-state radiation process e+e− → γI SRπ +π − J/ψ [1]. [8,9], Zhang and Huang construct the Cγ5 ⊗ ∂μ ⊗ γ5C type and Cγα ⊗ ∂μ ⊗ γ αC type vector interpolating currents, which have no definite charge conjugation, and study the vector tetraquark states with the QCD sum rules by taking into account the vacuum condensates up to dimension 6 in the operator product expansion, and obtain the masses 4.32 GeV and 4.69 GeV for the. The article is arranged as follows: we derive the QCD sum rules for the mass and pole residue of the vector tetraquark state Y (4260/4220) in Sect. We derive Eq (9) with respect to τ = T12 , eliminate the pole residue λY , and obtain the QCD sum rules for the mass of the vector tetraquark state Y (4260/4220), s0 4m2 ds d dτ ρ (s )

Numerical results and discussions

Conclusion