The Origin of Proton Mass from J/${\rm \Psi}$ Photo-production Data

Understand

The trace of the stress tensor characterizes the transformation of a theory under rescaling.

• In quantum chromodynamics (QCD), this trace contains contributions from the bare masses of the quarks and also from a purely quantum effect, called the QCD trace anomaly.
• It affects all masses in the theory.
• We present an estimation of the QCD trace anomaly from the near-threshold J/${\rm \Psi}$ photo-production data of the GlueX experiment, at JLab.