We show how nuclear effective field theory (EFT) and ab initio nuclear-structure methods can turn input from lattice quantum chromodynamics (LQCD) into predictions for the properties of nuclei. We argue that pionless EFT is the appropriate theory to describe the light nuclei obtained in recent LQCD simulations carried out at pion masses much heavier than the physical pion mass. We solve the EFT using the effective-interaction hyperspherical harmonics and auxiliary-field diffusion Monte Carlo methods. Fitting the three leading-order EFT parameters to the deuteron, dineutron and triton LQCD energies at mπ ≈ 800 MeV, we reproduce the corresponding alpha-particle binding and predict the binding energies of mass-5 and 6 ground states.PACS numbers: 21. 12.38.Gc Introduction -Understanding the low-energy dynamics of quantum chromodynamics (QCD), which underlies the structure of nuclei, is a longstanding challenge posed by its non-perturbative nature. After many years of development, lattice QCD (LQCD) simulations are fulfilling their promise of calculating static and dynamical quantities with controlled approximations. Progress has reached the point where meson and single-baryon properties can be predicted quite accurately, see for example Ref. [1]. Following the pioneering studies in quenched [2] and fully-dynamical [3] LQCD, a substantial effort is now in progress to study light nuclei [4][5][6][7]. Multinucleon systems are significantly more difficult to calculate than single-baryon states, as they are more complex, demand larger lattice volumes, and better accuracy to account for the fine-tuning of the nuclear force. At heavier light-quark masses, the formation of quark-antiquark pairs is suppressed, the computational resources required to generate LQCD configurations are reduced, and the signal-to-noise ratio in multinucleon correlation function improves [7]. Therefore, present multinucleon LQCD simulations are performed at heavy up and down quark masses, which result in unphysical values for hadronic quantities. Once lattice artifacts are accounted for using large enough volumes and extrapolating to the continuum, LQCD results depend on a single parameter, the pion mass m π . However, sufficiently large volumes are harder to achieve as the number of nucleons increases due to the the saturation of nuclear forces.

We extend the prediction range of Pionless Effective Field Theory with an analysis of the ground state of 16 O in leading order. To renormalize the theory, we use as input both experimental data and lattice QCD predictions of nuclear observables, which probe the sensitivity of nuclei to increased quark masses. The nuclear many-body Schrödinger equation is solved with the Auxiliary Field Diffusion Monte Carlo method. For the first time in a nuclear quantum Monte Carlo calculation, a linear optimization procedure, which allows us to devise an accurate trial wave function with a large number of variational parameters, is adopted. The method yields a binding energy of 4 He which is in good agreement with experiment at physical pion mass and with lattice calculations at larger pion masses. At leading order we do not find any evidence of a 16 O state which is stable against breakup into four 4 He, although higher-order terms could bind 16 O.

We address the Λ hypernuclear "overbinding problem" in light hypernuclei which stands for a 1-3 MeV excessive Λ separation energy calculated in _{Λ}^{5}He. This problem arises in most few-body calculations that reproduce ground-state Λ separation energies in the lighter Λ hypernuclei within various hyperon-nucleon interaction models. Recent pionless effective field theory (πEFT) nuclear few-body calculations are extended in this work to Λ hypernuclei. At leading order, the ΛN low-energy constants are associated with ΛN scattering lengths, and the ΛNN low-energy constants are fitted to Λ separation energies (B_{Λ}^{exp}) for A≤4. The resulting πEFT interaction reproduces in few-body stochastic variational method calculations the reported value B_{Λ}^{exp}(_{Λ}^{5}He)=3.12±0.02  MeV within a fraction of MeV over a broad range of πEFT cutoff parameters. Possible consequences and extensions to heavier hypernuclei and to neutron-star matter are discussed.

Binding energies of light, A ≤ 6, ΛΛ hypernuclei are calculated using the stochastic variational method in a pionless effective field theory (/ πEFT) approach at leading order with the purpose of assessing critically the onset of binding in the strangeness S = −2 hadronic sector. The / πEFT input in this sector consists of (i) a ΛΛ contact term constrained by the ΛΛ scattering length aΛΛ, using a range of values compatible with ΛΛ correlations observed in relativistic heavy ion collisions, and (ii) a ΛΛN contact term constrained by the only available A ≤ 6 ΛΛ hypernucler binding energy datum of 6 ΛΛ He. The recently debated neutral three-body and four-body systems 3 ΛΛ n and 4 ΛΛ n are found unbound by a wide margin. A relatively large value of |aΛΛ| 1.5 fm is needed to bind 4 ΛΛ H, thereby questioning its particle stability. In contrast, the particle stability of the A = 5 ΛΛ hypernuclear isodoublet 5 ΛΛ H-5 ΛΛ He is robust, with Λ separation energy of order 1 MeV. PACS numbers: Introduction. Single-Λ and double-Λ (ΛΛ) hypernuclei provide a unique extension of nuclear physics into strange hadronic matter [1]. Whereas the behavior of a single Λ hyperon in atomic nuclei has been deduced quantitatively by studying Λ hypernuclei ( A Λ Z) from A=3 to 208 [2], only three ΛΛ hypernuclei ( A ΛΛ Z) are firmly established: the lightest known 6 ΛΛ He Nagara event [3] and two heavier ones, 10 ΛΛ Be and 13 ΛΛ B [4]. Remarkably, their binding energies come out consistently in shell-model calculations [5]. Few ambiguous emulsion events from KEK [6] and J- PARC [7] have also been reported. However, and perhaps more significant is the absence of any good data on the onset of ΛΛ hypernuclear binding for A < 6. In distinction from the heavier species, these very light s-shell species, if bound, could be more affected by microscopic strangeness S = −2 dynamics. An obvious issue is the effect of a possible ΞN dominated H dibaryon resonance some 20-30 MeV above the ΛΛ threshold [8,9] on ΛΛ hypernuclear binding in general.Several calculations of light A < 6 s-shell ΛΛ hypernuclei using ΛΛ interactions fitted to 6 ΛΛ He suggest a fairly weak ΛΛ interaction, with the onset of ΛΛ hypernuclear binding defered to A = 4. Indeed, a slightly bound I = 0