Minding the gap between hard and diffractive structure functions at the EIC
arXiv:2607.12006
The authors formulate a fully differential factorization for gapped electron‑proton scattering at the EIC and demonstrate that the unpolarized azimuthally‑dependent and longitudinal structure functions vanish at leading power in ordinary hard scattering, so azimuthal dependence uniquely signals diffraction.
Abstract
Diffraction is characterized by forward scattering and a large rapidity gap. Ordinary hard scattering also produces gapped events and presents a significant background to identification of diffractively produced events. We present a fully differential factorization of gapped hard scattering. We find that the unpolarized azimuthally-dependent structure functions and the longitudinal vanish at leading power for hard scattering. Azimuthal dependence is thus a pure diffractive signature. This is borne out in Monte Carlo simulations.
7 pages, 2 figures + supplemental material (3 pages)