Chiral perturbation theory in few-body systems

Abstract

An effective hadronic field theory provides a framework to carry out systematic and consistent calculations of low-energy strong interaction processes. Its fundamental ingredient is chiral symmetry, which ensures a perturbative expansion of the nuclear potential in loops and many-nucleon effects. The two-nucleon potential to a certain order in this expansion provides a good fit to deuteron properties and to phase shifts up to 100 MeV laboratory energies. A consistent three-nucleon potential can also be obtained. Isospin violation from the quark mass difference and electromagnetism is shown to obey an observed hierarchy. Processes involving external probes—pion-deuteron scattering, proto-neutron radiative capture, pion photoproduction on the deuteron, and pion production in proton-proton collisions— are also discussed in the same framework.