Extraction of the proton mass radius from the vector meson photoproductions near thresholds

We present an analysis of the proton mass radius by studying $t$-dependence differential cross sections vector meson photoproductions near thresholds. At low energy, photoproduction a quarkonium off is connected to scalar gravitational form factor proton, which sensitive distribution from QCD trace anomaly. Under assumption dipole form, extracted via near-threshold data J/$\psi$, $\phi$ and $\omega$ mesons. The average value estimated be $\sqrt{\left} = 0.67\pm0.03$ fm, with cutoff $m_{\rm s}=1.01\pm0.04$ GeV.