New method for measuring the ratio μ p G E / G M based on the polarization transfer from the initial proton to the final electron in the ep → ep process

Abstract

In this paper, we propose a new method for measuring the Sachs form factors ratio (R = μpGE/GM) based on the transfer of polarization from the initial proton to the final electron in the elastic ep →ep process, in the case when the axes of quantization of spins of the target proton at rest and of the scattered electron are parallel, i.e., when an electron is scattered in the direction of the spin quantization axis of the proton target. To do this, in the kinematics of the SANE Collaboration experiment [A. Liyanage et al., Phys. Rev. C 101, 035206 (2020).] on measuring double-spin asymmetry in the ep→ ep process, using Kelly [Phys. Rev. C 70, 068202 (2004).] and Qattan et al. [Phys. Rev. C 91, 065203 (2015).] parametrizations, a numerical analysis was carried out of the dependence of the longitudinal polarization degree of the scattered electron on the square of the momentum transferred to the proton, as well as on the scattering angle of the electron. It is established that the difference in the longitudinal polarization degree of the final electron in the case of conservation and violation of scaling of the Sachs form factors can reach 70%. This fact can be used to set up polarization experiments of a new type to measure the ratio R.