Deuteron and exotic two-body bound states from lattice QCD

Abstract

Results of a high-statistics, multi-volume Lattice QCD exploration of the deuteron, the di-neutron, 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 − = 14.0(1.4)(6.7) MeV, consistent with expectations based upon phenomenological models and low-energy effective field theories constrained by nucleonnucleon and hyperon-nucleon scattering data at the physical light-quark masses. Further, we find that the deuteron and the di-neutron have binding energies of B d = 11(05)(12) MeV and B nn = 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.2

Strangeness in nuclei and neutron stars

“…In fact, the H-dibaryon, with quantum numbers of the ΛΛ system, has caught the attention of the χEFT and LQCD communities. The NPLQCD Collaboration provided evidence of a H-dibaryon bound state for m π ∼ 390 MeV [239,240], whereas the HAL QCD group determined also a bound state for m π ∼ 469 − 1171 MeV [241,242]. Extrapolations to the physical light-quark masses, however, pointed to a weakly bound H-dibaryon or a near-threshold state by the NPLQCD Collaboration [240,[243][244][245].…”

Mirage in temporal correlation functions for baryon-baryon interactions in lattice QCD

“…This also casts strong doubt on the recent works on the basis of the plateau fitting of the temporal correlations [2,3,16,[23][24][25][26][27][28][29][30][31][32][33][34][35][36], almost all of which claim the existence of bound multi-baryons (such as dineutron, deuteron, 3 He, 4 He, and other strange multi-baryons). At least, one should use more sophisticated approaches than the plateau fitting, such as the Bayesian fitting, Black box, or variational methods to extract the ground state energy from the temporal correlators (see e.g.…”

Nuclear Physics

“…It would be helpful if collaborations showed effective mass plots associated with the single-hadron and two-hadron systems, along with energy differences, in future publications. [34,20,18]. In contract, HALQCD does not find a bound deuteron at the heavier pion masses.…”