Lattice Nuclear Force
We derive an energy-independent and non-local potential for the baryon-baryon interaction from the Nambu-Bethe-Salpeter amplitude on the lattice. The method is applied to the nucleon-nucleon interactions with the (2+1)-flavor lattice QCD simulations. The central and tensor potentials are obtained as leading order terms of the velocity expansion of the non-local potential. The central potential has a repulsive core surrounded by an attractive well, while the tensor potential has intermediate and long range attractions. Validity of the velocity expansion is tested by the nucleon-nucleon interaction with finite relative momentum. Interactions among octet-baryons in the flavor SU (3) limit are also studied in full QCD simulations to unravel the origin of the repulsive core.