The Deuteron and Exotic Two-Body Bound States from Lattice QCD

Abstract

Results of a high-statistics, multivolume lattice QCD exploration of the deuteron, the dineutron, the H-dibaryon, and the Ξ − Ξ − system at a pion mass of m π ∼ 390 MeV are presented. Calculations were performed with an anisotropic n f = 2 + 1 clover discretization in four lattice volumes of spatial extent L ∼ 2.0 , 2.5, 2.9, and 3.9 fm, with a lattice spacing of b s ∼ 0.123 fm in the spatial direction and b t ∼ b s / 3.5 in the time direction. Using the results obtained in the largest two volumes, the Ξ − Ξ − is found to be bound by B Ξ − Ξ − 0 = 14.0 ( 1.4 ) ( 6.7 ) MeV , consistent with expectations based upon phenomenological models and low-energy effective field theories constrained by nucleon-nucleon and hyperon-nucleon scattering data at the physical light-quark masses. Further, we find that the deuteron and the dineutron have binding energies of B d = 11 ( 05 ) ( 12 ) MeV and B n n = 7.1 ( 5.2 ) ( 7.3 ) MeV , respectively. With an increased number of measurements and a refined analysis, the binding energy of the H-dibaryon is B H = 13.2 ( 1.8 ) ( 4.0 ) MeV at this pion mass, updating our previous result.