High-energy backward $\left(u\text{−}\text{channel}\right)$ reactions can involve very large momentum transfers to the target baryons, shifting them by many units of rapidity. These reactions are difficult to understand in conventional models in which baryon number is carried by the valence quarks. Backward Compton scattering is an especially attractive experimental target, because of its simple final state. There is currently limited data on this process, and those data are at low center-of-mass energies. In this paper, we examine the prospects for studying backward Compton scattering at the future Electron Ion Collider (EIC). We model the cross section and kinematics using the limited data on backward Compton scattering and backward meson production, and then simulate Compton scattering at EIC energies in a simple model of the ePIC detector. Generally, the proton is scattered toward midrapidity, while the produced photon is in the far-forward region, visible in a Zero Degree Calorimeter (ZDC). We show that the background from backward ${\pi }^0$ production can be rejected using a high-resolution, well-segmented ZDC.

• Received 23 August 2023
• Accepted 5 October 2023

DOI:https://doi.org/10.1103/PhysRevC.108.055205

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Published by the American Physical Society