On the Transfer of Polarization from the Initial to the Final Proton in the Elastic Process $ e \vec {p} \to e \vec {p}$

TL;DR

This paper analyzes how polarization is transferred from initial to final protons in elastic electron-proton scattering, highlighting the sensitivity of polarization transfer to form factor ratios and proposing a new measurement approach.

Contribution

It provides a numerical analysis of polarization transfer dependence on form factors and suggests a new experimental method for more reliable measurements.

Findings

Polarization transfer is sensitive to the $Q^2$ dependence of $rac{ ext{G}_E}{ ext{G}_M}$.

A criterion for assessing the reliability of form factor measurements was proposed.

Numerical results align with existing polarization experiment data.

Abstract

The $Q^2$ dependence of the ratio of the cross sections with and without proton spin flip, as well as the polarization asymmetry in the process $e \vec{p} \to e \vec{p}$ has been numerically analyzed using the results of JLab polarization experiments on the measurements of the ratio of the Sachs form factors in the $\vec{e} p \to e \vec{p}$ process. The calculations have been made for the case where the initial (at rest) and final protons are fully polarized and have a common spin quantization axis, which coincides with the direction of motion of the final proton. The longitudinal polarization transfer to the proton has been calculated in the case of the partially polarized initial proton for a kinematics used in the experiment reported in [A. Liyanage et al. (SANE Collaboration), Phys. Rev. C 101, 035206 (2020)], where the double spin asymmetry was measured in the $\vec{e} \vec{p} \to e p$ process. A noticeable sensitivity of the polarization transfer to the proton to the form of the $Q^2$ dependence of the ratio $\mu_p G_E/G_M$ has been found. This sensitivity may be used to conduct a new independent experiment to measure this dependence in the $ e \vec{p} \to e \vec{p}$ process. A criterion to assess the reliability of measurements of the ratio of Sachs form factors using the Rosenbluth technique has been proposed and used to analyze the results of two experiments.