The importance of the pion for nuclear physics has oscillated ever since its discovery in 1947 seemed to confirm a nuclear quantum field theory (QFT). Complexity intervened---the pion soon became just one of many hadrons and one of many elements of effective NN potentials needed in an ongoing effort to explain nuclear physics at distances larger than proton or pion size---structure of stable and unstable nuclei, neutron stars, nucleosynthesis, and related reactions.

Being the lightest and presumably the simplest hadron, the pion’s QCD substructure often serves to calibrate and test our quest for a QCD-based understanding at hadronic length scales. Surprizingly, there have been some longstanding puzzles about how QCD operates inside the pion; this holds back progress and limits our confidence in fundamental understanding of the nucleon, light nuclei, and ultimately nuclear dynamics.

I will discuss how the insides of the pion provide insights for fundamental hadron physics, and then I will describe developments of the past 2 years that have removed puzzles and clarified things immensely.

Argonne Physics Division Seminar Schedule