Scale-anomaly-induced confining pressure within hadrons

The effect of the QCD scale anomaly on the internal pressure distribution of hadrons is studied based on the trace-traceless decomposition of the energy-momentum tensor. Using recent model-independent results of gravitational form factors as input, the pressure distributions of both pions and nucleons are analyzed in the instant form and the light-front form. It is found that, in all cases, the scale anomaly dominantly generates the confining pressure. This result suggests that the phenomenon is a universal feature, independent of models, types of hadrons, and the choice of form.