Integrating Holographic Vector Dominance to Hidden Local Symmetry for the Nucleon Form Factor

TL;DR

This paper develops a two-parameter holographic model for nucleon electromagnetic form factors, fitting experimental data well at low momentum transfer and highlighting the significance of the infinite meson tower in nucleon structure.

Contribution

It introduces a simplified two-parameter formula derived from holographic QCD that effectively models nucleon form factors, emphasizing the role of the infinite meson tower.

Findings

The model fits experimental data for $Q^2\lesssim 0.5$ GeV$^2$ with low chi-squared.

The infinite tower of vector mesons is crucial for nucleon structure.

The holographic model captures the proton's core size and internal structure.

Abstract

We derive a two-parameter formula for the electromagnetic form factors of the nucleon described as an instanton by "integrating out" all KK modes other than the lowest mesons from the infinite-tower of vector mesons in holographic QCD while preserving hidden local symmetry for the resultant vector fields. With only two parameters, the proton Sachs form factors can be fit surprisingly well to the available experimental data for momentum transfers $Q^2\lsim 0.5$ GeV$^2$ with $\chi^2$/dof $\lsim 2$. We interpret this agreement as indicating the importance of an infinite tower in the soliton structure of the nucleon. The prediction of the Sakai-Sugimoto holographic dual model is checked against the fit values to assess its accuracy in describing the proton structure. We find that the structure of the "core" of roughly 1/3 in the proton size indicated in experiments and commonly associated with an intrinsic quark-gluon structure in QCD is "hidden" in the infinite tower in the holographic model.