Vector tetraquark state candidates: Y(4260 / 4220), Y(4360 / 4320), Y(4390) and Y(4660 / 4630)

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2018-06, Vol.78 (6), p.1-12, Article 518
• Main Author: Wang, Zhi-Gang
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics and Cosmology; Elementary Particles; Hadrons; Heavy Ions; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Operators (mathematics); Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular Article - Theoretical Physics; String Theory; Sum rules
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-018-5996-5

In this article, we construct the C ⊗ γ μ C and C γ 5 ⊗ γ 5 γ μ C type currents to interpolate the vector tetraquark states, then carry out the operator product expansion up to the vacuum condensates of dimension-10 in a consistent way, and obtain four QCD sum rules. In calculations, we use the formula μ = M Y 2 - ( 2 M c ) 2 to determine the optimal energy scales of the QCD spectral densities, moreover, we take the experimental values of the masses of the Y (4260 / 4220), Y (4360 / 4320), Y (4390) and Y (4660 / 4630) as input parameters and fit the pole residues to reproduce the correlation functions at the QCD side. The numerical results support assigning the Y (4660 / 4630) to be the C ⊗ γ μ C type vector tetraquark state c c ¯ s s ¯ , assigning the Y (4360 / 4320) to be C γ 5 ⊗ γ 5 γ μ C type vector tetraquark state c c ¯ q q ¯ , and disfavor assigning the Y (4260 / 4220) and Y (4390) to be the pure vector tetraquark states.