Study of the ${\mathrm{\Omega }}_{ccc}{\mathrm{\Omega }}_{ccc}$ and ${\mathrm{\Omega }}_{bbb}{\mathrm{\Omega }}_{bbb}$ dibaryons in QCD Sum Rules

The recent observation of a family of fully-charm tetraquark states by the LHCb, ATLAS and CMS Collaborations suggests the possible existence of fully-heavy dibaryons. In this work, we investigate the ${\mathrm{\Omega }}_{ccc}{\mathrm{\Omega }}_{ccc}$ and ${\mathrm{\Omega }}_{bbb}{\mathrm{\Omega }}_{bbb}$ dibaryons in both the ${}^1{S}_0$ and ${}^5{S}_2$ channels using the method of QCD sum rules. We employ the iterative dispersion relation (IDR) method to efficiently compute the massive five-loop banana diagrams that appear in these systems, and properly address the tricky small-circle divergence problem in the nonperturbative terms. Our analyses reveal that for both charm and bottom systems, the scalar dibaryon lies lower than its tensor counterpart. In $\overline{\text{MS}}$ scheme, the mass of the scalar ${\mathrm{\Omega }}_{ccc}{\mathrm{\Omega }}_{ccc}$ dibaryon is found to be slightly above the $2{\mathrm{\Omega }}_{ccc}$ mass threshold, while the ${\mathrm{\Omega }}_{bbb}{\mathrm{\Omega }}_{bbb}$ systems may form bound states. However, they are predicted to be much heavier in the on-shell scheme.