Fully charmed tetraquark states in 8[cc̄]⊗ 8[cc̄] color structure via QCD sum rules

Stimulated by the recent experimental results on the fully-charm tetraquark states, we systematically calculate the mass spectra of the fully-charm tetraquark states in 8[cc̄]⊗ 8[cc̄] 8 [ c c ¯ ] ⊗ 8 [ c c ¯ ] color configuration via QCD sum rules. By constructing nine 8[cc̄]⊗ 8[cc̄] 8 [ c c ¯ ] ⊗ 8 [ c c ¯ ] type currents with quantum numbers JPC=0⁻⁺,0⁻⁻,1⁻⁺,1⁺⁻,1⁻⁻ J PC = 0 - + , 0 - - , 1 - + , 1 + - , 1 - - and 2⁺⁺ 2 + + , we perform analytic calculation up to dimension six in the operator product expansion (OPE). We find the fully-charm tetraquark states with JPC=1⁺⁻,2⁺⁺ J PC = 1 + - , 2 + + lie around 6.48 ~ ∼ 6.62 GeV while the fully-charm tetraquark states with JPC=0⁻⁺,0⁻⁻,1⁻⁻,1⁻⁺ J PC = 0 - + , 0 - - , 1 - - , 1 - + are about 6.85 ~ ∼ 7.02 GeV. Notably, the mass predictions for the cc̄cc̄ c c ¯ c c ¯ tetraquarks, specifically those with JPC=2⁺⁺ J PC = 2 + + , align with the broad structure identified by LHCb. Moreover, the masses of fully-charm tetraquarks with JPC=0⁻⁺ J PC = 0 - + and 1⁻⁺ 1 - + are anticipated to match closely with the mass of X(6900), considering the margin of error. Such findings hint at the presence of some 8[cc̄]⊗ 8[cc̄] 8 [ c c ¯ ] ⊗ 8 [ c c ¯ ] components within the di- J/ψ J / ψ structures observed by LHCb. The predictions for tetraquark states with JPC=0⁻⁻,1⁺⁻,1⁻⁻ J PC = 0 - - , 1 + - , 1 - - may be accessible in the future BelleII, Super-B, PANDA, and LHCb experiments.