Emergence of Hadron Mass

Determine the mechanism by which hadron mass emerges from Quantum Chromodynamics by identifying and quantitatively explaining the strong-interaction dynamics that generate the dominant portion of hadron masses beyond the small contribution from current-quark masses.

Background

The paper emphasizes that the masses of hadrons, such as the nucleon, cannot be accounted for by the sum of the bare quark masses appearing in the QCD Lagrangian, which contribute less than 2% of the nucleon mass. This indicates that the dominant share of hadron mass must arise from strong-interaction dynamics within QCD, rather than the Higgs mechanism.

Within the continuum Schwinger method framework, dynamical mass generation for gluons and quarks is connected to the behavior of the QCD running coupling and dressing effects, leading to momentum-dependent mass functions. The authors argue that measurements of the Q^2 evolution of N* electroexcitation amplitudes (electrocouplings) from CLAS and CLAS12 provide a way to map the dressed quark mass function, thereby offering insight into the unresolved problem of how hadron mass emerges from QCD.