Deuteronlike Heavy Dibaryons from Lattice Quantum Chromodynamics.

Abstract

We report the first lattice quantum chromodynamics (QCD) study of deuteronlike (np-like) dibaryons with heavy quark flavors. These include particles with the following dibaryon structures and valence quark contents: Σ_{c}Ξ_{cc}(uucucc), Ω_{c}Ω_{cc}(sscscc), Σ_{b}Ξ_{bb}(uububb), Ω_{b}Ω_{bb}(ssbsbb), and Ω_{ccb}Ω_{cbb}(ccbcbb), and with spin (J) parity (P), J^{P}≡1^{+}. Using a state-of-the art lattice QCD calculation, after controlling relevant systematic errors, we unambiguously find that the ground state masses of dibaryons Ω_{c}Ω_{cc}(sscscc), Ω_{b}Ω_{bb}(ssbsbb), and Ω_{ccb}Ω_{cbb}(ccbcbb) are below their respective two-baryon thresholds, suggesting the presence of bound states that are stable under strong and electromagnetic interactions. We also predict their masses precisely. For dibaryons Σ_{c}Ξ_{cc}(uucucc), and Σ_{b}Ξ_{bb}(uububb), we could not reach to a definitive conclusion about the presence of any bound state due to large systematics associated with these states. We also find that the binding of these dibaryons becomes stronger as they become heavier in mass. This study also opens up the possibility of the existence of many other exotic nuclei, which can be formed through the fusion of heavy baryons, similar to the formation of nuclei of elements in the periodic table.