Proton and deuteron mass radii from near-threshold $\phi$-meson photoproduction

TL;DR

This study determines the proton and deuteron mass radii using near-threshold $$-meson photoproduction data, revealing their sizes and the sensitivity of quarkonium production to hadronic system radii.

Contribution

It provides the first combined analysis of proton and deuteron mass radii from near-threshold $$-meson photoproduction data, applying a scalar gravitational form factor model.

Findings

Proton mass radius: 0.75 1 0.02 fm

Deuteron mass radius: 1.95 1 0.19 fm

Data well described by vector-meson-dominance model

Abstract

We analyze the exclusive $\phi$-meson photoproduction on both hydrogen and deuterium targets based on the published data of CLAS, SAPHIR and LEPS collaborations. A dipole-form scalar gravitational form factor is applied to describe the $|t|$-dependence of the differential cross section. Based on the average of all the near-threshold data from CLAS, SAPHIR and LEPS, we find that the proton and deuteron mass radii are $0.75 \pm 0.02$ fm and $1.95 \pm 0.19$ fm respectively. The coherent and near-threshold quarkonium photoproduction seems to be sensitive to the radius of the hadronic system. The vector-meson-dominance model together with a low-energy QCD theorem well describe the data of near-threshold $\phi$ photoproduction on the hadronic systems.