Color Transparency and the Proton Form Factor- Feynman Wins

TL;DR

This paper uses superconformal symmetry and light-front holographic QCD to analyze a recent experiment, concluding that the absence of color transparency effects supports the Feynman mechanism as the main process for the proton's high momentum form factor.

Contribution

It introduces a new formalism based on superconformal symmetry and holographic QCD to analyze color transparency and the proton form factor.

Findings

Expansion effects are insufficient to cause final state interactions.

No evidence of point-like-configuration formation in the experiment.

Feynman mechanism dominates the proton's high momentum form factor.

Abstract

A recent experiment [{\bf Phys. Rev. Lett. 126,082301 (2021)}] used the $(e,e'p)$ reaction on $^{12}$C to search for the effects of color transparency (the absence of final state interactions). Color transparency was said to be ruled out. The ability to observe the effects of color transparency depends on the ability of a putative point-like-configuration (PLC), formed in a high-momentum transfer coherent reaction, to escape the nucleus without expanding its size. We study the expansion aspect of color transparency using superconformal baryon-meson symmetry and light-front holographic QCD. A new formalism is obtained and used to analyze the recent experiment. The resulting conclusion is that effects of expansion would not be sufficiently significant in causing final state interactions to occur. Therefore we conclude that a PLC was not formed. This means that the Feynman mechanism involving virtual photon absorption on a single high momentum quark is responsible for high momentum electromagnetic form factor of the proton.