Scalar-glueball-mediated scale-anomaly dominance of the confining pressure of the pion in holographic QCD

Fujii, Daisuke; Iwanaka, Akihiro*; Tanaka, Mitsuru*

In this study, we investigate the internal energy and stress distribution of the pion, as extracted from gravitational form factors within a top-down holographic QCD framework. We demonstrate that the confining pressure inside the pion is also predominantly governed by the QCD scale anomaly, consistent with earlier findings for the nucleon in the instant form, now confirmed in the light-front form for the pion. Furthermore, our analysis shows that, in the large- limit realized in this holographic setup, the scalar glueball acts as the mediator of the confining pressure. These results provide further evidence for the universal role of the scale anomaly in hadron stability.