Minding the gap between hard and diffractive structure functions at the EIC

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 $ep$ scattering. We find that the unpolarized azimuthally-dependent structure functions $F_{3,4}^{\mathrm{gap}}$ and the longitudinal $F_L^{\mathrm{gap}}$ vanish at leading power for hard scattering. Azimuthal dependence is thus a pure diffractive signature. This is borne out in Monte Carlo simulations.

Comments: 7 pages, 2 figures + supplemental material (3 pages)