Systematic analysis of the proton mass radius based on photoproduction of vector charmoniums

TL;DR

This paper systematically analyzes the proton mass radius using photoproduction of vector charmoniums within a two gluon exchange model, providing numerical estimates consistent with experimental data and discussing implications for nucleon structure.

Contribution

It introduces a systematic analysis of the proton mass radius from vector charmonium photoproduction data using a two gluon exchange model, with new numerical estimates and insights.

Findings

Proton mass radius estimated as 0.55±0.09 fm from J/ψ data.

Proton mass radius estimated as 0.77±0.12 fm from ψ(2S) data.

Average proton mass radius is approximately 0.67±0.11 fm.

Abstract

In this work, the cross-section of the reaction $\gamma p \rightarrow V(J/\psi,\psi(2S)) p$ from the production threshold to medium energy is studied and systematically analyzed within two gluon exchange model. The obtained numerical results are in agreement with experimental data and other theoretical predictions. Under the assumption of the scalar form factor of dipole form, the value of proton mass radius is calculated as $0.55\pm 0.09$ fm and $ 0.77\pm 0.12$ fm from the fit to the predicted $J/\psi $ and $\psi(2S)$ differential cross-section, respectively. Finally the average value of proton mass radius is estimated to be $\sqrt{\left<R^2_m \right>}=0.67\pm 0.11$ fm. Moreover, one find that extracting mass radius from the near-threshold differential cross-section of heavy quarkoniums is always affected by large $|t|_{min}$. These obtained results may provide important theoretical reference for understanding of nucleon structure and future relevant experiments.