  Quark mass dependence of the equation of state (EOS) for nucleonic matter is
investigated, on the basis of the Brueckner-Hartree-Fock method with the
nucleon-nucleon interaction extracted from lattice QCD simulations. We observe
saturation of nuclear matter at the lightest available quark mass corresponding
to the pseudoscalar meson mass ~ 469 MeV. Mass-radius relation of the neutron
stars is also studied with the EOS for neutron-star matter from the same
nuclear force in lattice QCD. We observe that the EOS becomes stiffer and thus
the maximum mass of neutron star increases as the quark mass decreases toward
the physical point.
