Nuclear Dependence of Beam Normal Single Spin Asymmetry in Elastic Scattering from Nuclei

TL;DR

This paper proposes measuring the beam normal single spin asymmetry in elastic electron scattering from various nuclei to explore nuclear dependence and address discrepancies between theory and experimental data, especially for heavy nuclei.

Contribution

It introduces new measurements of beam normal single spin asymmetry for nuclei with 12 ≤ Z ≤ 90, filling gaps in existing data and testing theoretical models at low Q².

Findings

Discrepancy observed in 208Pb data compared to theory.

New data will help understand missing contributions in models.

Study covers nuclei with Z from 12 to 90.

Abstract

We propose to measure the beam normal single spin asymmetry in elastic scattering of transversely polarized electron from target nuclei with 12 $\leq Z \leq$ 90 at Q$^2$ = 0.0092 GeV$^2$ to study its nuclear dependence. While the theoretical calculations based on two-photon exchange suggest no nuclear dependence at this kinematics, the results of 208Pb from Jefferson Lab show a striking disagreement from both theoretical predictions and light nuclei measurements. The proposed measurements will provide new data for intermediate to heavy nuclei where no data exists for $Z \geq$ 20 in the kinematics of previous high-energy experiments. It will allow one to investigate the missing contributions that are not accounted in the current theoretical models.