Discovery of the doubly charmed Tcc+ state implies a triply charmed Hccc hexaquark state

The doubly charmed exotic state Tcc recently discovered by the LHCb Collaboration could well be a DD∗ molecular state long predicted in various theoretical models, in particular, the DD∗ isoscalar axial vector molecular state predicted in the one-boson-exchange model. In this work, we study the DDD∗ system in the Gaussian expansion method with the DD∗ interaction derived from the one-boson-exchange model and constrained by the precise binding energy of 273±63 keV of Tcc with respect to the D∗+D0 threshold. We show the existence of a DDD∗ state with a binding energy of a few hundred keV, isospin 1/2, and spin-parity 1-. Its main decay modes are DDDπ and DDDγ. The existence of such a state could in principle be confirmed with the upcoming LHC data and will unambiguously determine the nature of the Tcc+ state and of the many exotic states of similar kind, thus deepening our understanding of the nonperturbative strong interaction.