Atomic nuclei lie at the core of everything we can see. At the first level of approximation, their atomic weights are simply the sum of the masses of all the neutrons and protons (nucleons) they contain. Each nucleon has a mass m_N ≈ 1 GeV, i.e. approximately 2000-times the electron mass. The Higgs boson produces the latter, but what produces the masses of the neutron and proton? This is the crux: the vast bulk of the mass of a nucleon is lodged with the energy needed to hold quarks together inside it; and that is supposed to be explained by quantum chromodynamics (QCD), the Standard Model’s strong-interaction piece. Science has never before encountered an interaction such as that in QCD. Charting this interaction can potentially change the way we look at the Universe. This presentation will canvass the scope for a coherent effort in experiment and theory to reveal the origin and distribution of mass within hadrons, highlighting experiments approved at JLab; planned with COMPASS at CERN; and possible with the unique capabilities foreseen at an electron ion collider.

Argonne Physics Division Colloquium Schedule