Scalar fully-heavy tetraquark states QQ′(Q)over-bar(Q)over-bar′ in QCD sum rules

Very recently, the LHCb Collaboration observed distinct structures with the cc (c) over bar(c) over bar in the J/Psi-pair mass spectrum. In this work, we construct four scalar (J PC = 0(++)) [8(c)](Q (Q) over bar),circle times[8(c)](Q'(Q) over bar) type currents to investigate the fully-heavy tetraquark state QQ (Q) over bar(Q) over bar' in the framework of QCD sum rules, where Q = c, b and Q' = c, b. Our results suggest that the broad structure around 6.2-6.8 GeV can be interpreted as the 0(++) octet-octet tetraquark stateswith masses 6.44 +/- 0.11 GeV and 6.52 +/- 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 +/- 0.11 GeV and 6.96 +/- 0.11 GeV, respectively. 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 [8(c)](c (c) over bar) circle times [8(c)](b (b) over bar) and [8(c)](c (b) over bar). [8(c)](b (c) over bar) tetraquark states, which lie in the range of 12.51-12.74 GeV and 12.49-12.81 GeV, respectively.

Automated summary

Researchers identified distinct structures in the J/Psi-pair mass spectrum as different masses of tetraquark states using QCD sum rules. The octet-octet tetraquark states were found to have masses around 6.44-6.96 GeV, with corresponding fully-bottom partners around 18.38-18.59 GeV.