Scalar Fully-heavy Tetraquark States $Q{Q}^{\prime }\bar{Q}\overline{Q^{\prime }}$ in QCD Sum Rules

Abstract

Very recently, the LHCb Collaboration observed distinct structures with the $cc\bar{c}\bar{c}$ in the $J/\Psi$-pair mass spectrum. In this work, we construct four scalar ($J^{PC}=0^{++}$) $[8_c{]}_{Q\overline{Q^{\prime }}}\otimes [8_c{]}_{Q^{\prime }\bar{Q}}$ type currents to investigate the fully-heavy tetraquark state $Q{Q}^{\prime }\bar{Q}\overline{Q^{\prime }}$ in the framework of QCD sum rules, where $Q=c,b$ and $Q^{\prime }=c,b$. Our results suggest that the broad structure around 6.2-6.8 GeV can be interpreted as the $0^{++}$ octet-octet tetraquark states with masses $6.44\pm 0.11$ GeV and $6.52\pm 0.10$ GeV, and the narrow structure around $6.9$ GeV can be interpreted as the $0^{++}$ octet-octet tetraquark states with masses $6.87\pm 0.11$ GeV and $6.96\pm 0.11$ GeV, respectivley. Extending to the b-quark sector,the masses of their fully-bottom partners are found to be around 18.38-18.59 GeV. Additionally, we also analyze the spectra of the $[c\bar{c}][b\bar{b}]$ and $[c\bar{b}][b\bar{c}]$ tetraquark states, which lie in the range of 12.51-12.74 GeV and 12.49-12.81 GeV, respectively.

Comments: 18 pages, 1 figures, 2 tables, version published in EPJC