Exploration of trace anomaly contribution to proton mass based on light vector meson photoproduction

TL;DR

This paper quantifies the trace anomaly's contribution to proton mass using light vector meson photoproduction data, revealing it accounts for about 4.36% of the proton's total mass, thus advancing understanding of proton internal structure.

Contribution

It introduces a method to extract the trace anomaly contribution to proton mass from experimental photoproduction data of light vector mesons.

Findings

Trace anomaly contributes approximately 4.36% to proton mass.

Extracted contributions for $ ho$, $ ext{omega}$, and $ ext{phi}$ mesons.

Provides quantitative insight into proton internal structure.

Abstract

In the quantum chromodynamics, the mass source of the proton is decomposed into four parts by the energy momentum tensor : quark energy term, gluon energy term, quark mass term and trace anomaly term. And the trace anomaly term is the most crucial contribution for studying the internal structure of the proton. In this work, under the definition of the vector meson dominant model, the trace anomaly contribution of the proton is extracted from the experimental datas of light vector mesons $\rho$, $\omega$ and $\phi$ photoproduction at the near-threshold, which are ($1.15\pm0.08$)$\%$, ($2.70\pm0.04$)$\%$ and ($5.58\pm0.25$)$\%$, respectively. Eventually, the average trace anomaly contribution of the proton is ($4.36\pm0.40$) $\%$, which only account for a small fraction of the total proton mass. The result of this work will provide theoretical information support for further study of proton internal structure.