Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India.
Phys Rev Lett. 2019 Oct 18;123(16):162003. doi: 10.1103/PhysRevLett.123.162003.
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.
我们报告了第一个格点量子色动力学（QCD）对重夸克味的氘类似（np 类似）双介子的研究。这些包括以下双介子结构和价夸克内容的粒子：Σ_{c}Ξ_{cc}(uucucc)、Ω_{c}Ω_{cc}(sscscc)、Σ_{b}Ξ_{bb}(uububb)、Ω_{b}Ω_{bb}(ssbsbb)和Ω_{ccb}Ω_{cbb}(ccbcbb)，以及自旋（J）宇称（P），J^{P}≡1^{+}。使用最先进的格点 QCD 计算，在控制相关系统误差后，我们明确地发现双介子 Ω_{c}Ω_{cc}(sscscc)、Ω_{b}Ω_{bb}(ssbsbb)和 Ω_{ccb}Ω_{cbb}(ccbcbb)的基态质量低于它们各自的双介子阈值，表明存在稳定于强相互作用和电磁相互作用的束缚态。我们还准确地预测了它们的质量。对于双介子 Σ_{c}Ξ_{cc}(uucucc)和 Σ_{b}Ξ_{bb}(uububb)，由于与这些态相关的大系统误差，我们无法对任何束缚态的存在得出明确的结论。我们还发现，随着双介子质量的增加，它们的束缚变得更强。这项研究也为许多其他奇异核的存在提供了可能性，这些核可以通过重子的融合形成，类似于元素周期表中元素核的形成。
