The Dirac Form Factor Predicts the Pauli Form Factor in the Endpoint Model

TL;DR

This paper demonstrates that the endpoint overlap model accurately predicts the proton's Pauli form factor and its ratio with the Dirac form factor, aligning with experimental data without adjustable parameters.

Contribution

It shows that the endpoint overlap model, using leading-power light-cone wave functions, can predict the proton form factors consistently with experimental observations.

Findings

The model reproduces the $F_2/F_1$ ratio scaling observed at Jefferson Laboratory.

Predicted ratio $F_2(Q^2)/F_1(Q^2)$ is insensitive to endpoint wave function variations.

The endpoint model is consistent with all form factor data and large momentum transfer scattering.

Abstract

We compute the momentum-transfer dependence of the proton Pauli form factor $F_{2}$ in the endpoint overlap model. We find the model correctly reproduces the scaling of the ratio of $F_{2}$ with the Dirac Form factor $F_{1}$ observed at the Jefferson Laboratory. The calculation uses the leading-power, leading twist Dirac structure of the quark light-cone wave function, and the same endpoint dependence previously determined from the Dirac form factor $F_{1}$. There are no parameters and no adjustable functions in the endpoint model's prediction for $F_{2}$. The model's predicted ratio $F_{2}(Q^{2})/F_{1}(Q^{2})$ is quite insensitive to the endpoint wave function, which explains why the observed ratio scales like $1/Q$ down to rather low momentum transfers. The endpoint model appears to be the only comprehensive model consistent with all form factor information as well as reproducing fixed-angle proton-proton scattering at large momentum transfer. Any one of the processes is capable of predicting the others.