Systematic study of fully heavy-flavored tetraquarks Q 1 Q 2 Q ¯ 1 Q ¯ 2 ( Q 1 , 2 ∈ { b , c } ): Mass spectra, threshold analysis, and confrontation with LHC data

Experimental searches for fully heavy flavored tetraquark states are actively pursued at the LHC. The LHCb, CMS, and ATLAS collaborations have investigated fully charmed c c c ¯ c ¯ , doubly charmed-bottom b c b ¯ c ¯ and fully bottom b b b ¯ b ¯ tetraquarks. Fully charmed states are probed as intermediate resonances in processes like p + p → J / ψ J / ψ and p + p → J / ψ μ + μ − at s = 7 , 8 , and 13 TeV. Notably, narrow structures such as X ( 6200 ) , X ( 6900 ) , and X ( 7300 ) observed in the di- J / ψ mass spectrum have ignited theoretical interest. In this study, we use a nonrelativistic model to perform a detailed study of the mass spectra for the ground ( 1 S ) and excited ( 1 P , 2 S , 1 D , 2 P , 3 S , and 4 S ) states of fully heavy tetraquarks Q 1 Q 2 Q ¯ 1 Q ¯ 2 ( Q 1 , 2 ∈ { b , c } ) in the diquark-antiquark picture. Tetraquarks are modeled as color-singlet bound states build from an axial-vector diquark ( [ Q 1 Q 2 ] s = 1 ) and axial-vector antidiquark (