Study of the $\hat{I}{\text{c◯}}_{ccc}\hat{I}{\text{c◯}}_{ccc}$ and $\hat{I}{\text{c◯}}_{bbb}\hat{I}{\text{c◯}}_{bbb}$ dibaryons in QCD Sum Rules

Abstract

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 $\hat{I}{\text{c◯}}_{ccc}\hat{I}{\text{c◯}}_{ccc}$ and $\hat{I}{\text{c◯}}_{bbb}\hat{I}{\text{c◯}}_{bbb}$ 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 $\hat{I}{\text{c◯}}_{ccc}\hat{I}{\text{c◯}}_{ccc}$ dibaryon is found to be slightly above the $2\hat{I}{\text{c◯}}_{ccc}$ mass threshold, while the $\hat{I}{\text{c◯}}_{bbb}\hat{I}{\text{c◯}}_{bbb}$ systems may form bound states. However, they are predicted to be much heavier in the on-shell scheme.

8 pages, 7 figures. Accepted for publication on Physical Review D