Gravitational form factors of the proton in the improved holographic QCD model

TL;DR

This paper calculates the gluonic contribution to the proton's gravitational form factors using an improved holographic QCD model, providing insights into the proton's internal mechanical and mass distributions.

Contribution

It introduces a novel holographic QCD approach constrained by lattice and phenomenological data to estimate the proton's gravitational form factors, especially the gluonic part.

Findings

Gluonic form factor $ ext{D}(t)$ exhibits an infrared pole.

Estimated mechanical radius of the proton is approximately 0.95 fm.

Estimated mass radius of the proton is approximately 0.61 fm.

Abstract

We compute the gluonic contribution to the gravitational form factors of the proton using the improved holographic QCD model, in which the proton is described in terms of bulk Dirac fermions. Model parameters are constrained using lattice and phenomenological input, allowing us to obtain estimates for the gravitational form factors and to compare them with results from other approaches. The resulting gluonic contribution to the $\mathcal{D}(t)$ form factor is found to exhibit an infrared pole in our framework. Using the extracted form factors, we analyze mechanical properties of the proton, including pressure and shear distributions. We obtain estimates of $\rho_{\text{mech}} = 0.95$ fm and $\rho_{\text{mass}} = 0.61$ fm for the mechanical and the mass radii of the proton, respectively, which are similar to other nonperturbative studies.