Deuteron and exotic two-body bound states from lattice QCD

Results of a high-statistics, multivolume lattice QCD exploration of the deuteron, the dineutron, the H-dibaryon, and the ^-^- system at a pion mass of m_390 MeV are presented. Calculations were performed with an anisotropic n₅=2+1 clover discretization in four lattice volumes of spatial extent L2. 0, 2. 5, 2. 9, and 3. 9 fm, with a lattice spacing of bₒ0. 123 fm in the spatial direction and bₓbₒ/3. 5 in the time direction. Using the results obtained in the largest two volumes, the ^-^- is found to be bound by B^{-^-}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 B₃=11 (05) (12) MeV and B₍₍=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 B₇=13. 2 (1. 8) (4. 0) MeV at this pion mass, updating our previous result.