NUCLEAR FORCES AND STRUCTURE
How do protons and neutrons bind to form nuclei? While the answer may seem as simple as the fact that nuclear forces are attractive, the full story is more complex and interesting. Ab initio lattice simulations show that nature is near a quantum phase transition, a zero-temperature transition driven by quantum fluctuations. For even and equal numbers of protons and neutrons, a first-order transition is found at zero temperature from a Bose-condensed gas of alpha particles to a nuclear liquid. Whether one has an alpha-particle gas or nuclear liquid is determined by the strength of the alpha-alpha interactions, and the alpha-alpha interactions depend on the strength and locality of the nucleon-nucleon interactions.