Study Of The Fully-heavy Tetraquark States In QCD Sum Rules

In 2020,the LHCb Collaboration observed distinct structures made up of two charmanti charm pairs,cc(?).in the invariant J/?-pair mass spectrum.In this work,we construct four scalar(J^PC=0⁺⁺)[8_c]_Q(?)(?)[8_c]_Q'(?) type currents to investigate the fully-heavy tetraquark state QQ'Q(?) in the framework of QCD sum rules,whereQ=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 states with 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 bquark sector,the masses of their 0⁺⁺fully-bottom partners are found to be around 18.3818.59 GeV.Additionally,we also analyze the spectra of the[8_c]_c(?)(?)[8_c]_b(?) and[8_c]_c(?)(?)[8c]bc tetraquark states,which lie in the range of 12.51-12.74 GeV and 12.49-12.81 GeV,respectively.Moreover,we also extend our study to several other normal quantum numbers,such as J^PC=0^-+,1^±-,2⁺⁺.These studies will provide valuable theoretical predictions for the near futher experimets.