Neutron Spin Structure from e-3He Scattering with Double Spectator Tagging at the Electron-Ion Collider

TL;DR

This paper proposes a double spectator tagging method at the Electron-Ion Collider to accurately measure the neutron's spin structure, significantly reducing nuclear model dependencies and uncertainties in experimental results.

Contribution

The study introduces a novel double spectator tagging technique at the EIC to suppress nuclear effects in neutron spin structure measurements, enhancing precision over existing methods.

Findings

Double spectator tagging reduces uncertainties by a factor of 4 overall.

In the low-xB region, uncertainties decrease by a factor of 10.

The method enables probing neutron spin structure from xB of 0.003 to 0.651.

Abstract

The spin structure function of the neutron is traditionally determined by measuring the spin asymmetry of inclusive electron deep inelastic scattering (DIS) off polarized3He nuclei. In such experiments, nuclear effects can lead to large model dependencies in the interpretation of experimental data. Here we study the feasibility of suppressing such model dependencies by tagging both spectator protons in the process of DIS off neutrons in3He at the forthcoming Electron-Ion Collider (EIC). This allows reconstructing the momentum of the struck neutron to ensure it was nearly at rest in the initial state, thereby reducing sensitivity to nuclear corrections, and suppress contributions from electron DIS off protonsin3He. Using realistic accelerator and detector configurations, we find that the EIC can probe the neutron spin structure from xB of 0.003 to 0.651. We further find that the double spectator tagging method results in reduced uncertainties bya factor of 4 on the extracted neutron spin asymmetries over all kinematics, and by a factor of 10 in the low-xB region,thereby providing valuable insight to the spin and flavor structure of nucleons