Scattering theory is a framework connecting seemingly different phenomena of the quantum world such as stable bound states, resonances, elastic scattering, and reactions. It has applications in many areas of physics, ranging from hadrons and nuclear physics to the description of ultracold atomic systems. In particular, scattering theory provides the foundation for few- and many-body approaches that solve quantum problems from first principles, and it is an essential ingredient for the description of low-energy nuclear reactions that will be studied at the Facility for Rare Isotope Beams (FRIB).

The PREX-2 collaboration has measured the parity-violating electroweak asymmetry in the elastic scattering of longitudinally polarized electrons from the lead-208 nucleus. This long-sought measurement determines the nuclear weak form-factor at the measurement kinematics. The result provides important constraints on the neutron skin in Pb-208 and on the density dependence of the symmetry energy in neutron-rich nuclear matter near saturation density. The interpretation of the result is precise and model independent, with a small and well-estimated theoretical uncertainty. An overview of the experimental technique and results will be presented.