Gluon Radiation in Diffractive Electroproduction
W. Buchmuller, A. Hebecker, M. F. McDermott
TL;DR
The paper develops a semiclassical framework for hard diffractive electroproduction by modeling the proton as a classical colour field and computing diffractive structure functions through external-field scattering and Wilson-line correlators. It extends previous quark-pair analyses to include gluon radiation, deriving diffractive contributions from final states with two high-$p_T$ jets and a soft gluon, and shows that $F_L^D$ is a leading-twist quantity only in the gluon-radiation channels, while $F_2^D$ carries substantial nonperturbative content encoded in the proton field averages. The results yield an aligned-jet-like picture for diffraction, with high-$p_T$ jets contributing to diffractive observables in a controlled, perturbative manner, and nonperturbative soft interactions governing the $eta$-dependence of diffractive spectra. Overall, the work provides a calculational route linking soft proton structure to hard diffractive jet phenomena and outlines future work on energy dependence and higher-order corrections.
Abstract
Order $α_s$-corrections to the diffractive structure functions $F_L^D$ and $F_2^D$ at large $Q^2$ and small $x$ are evaluated in the semiclassical approach, where the initial proton is treated as a classical colour field. The diffractive final state contains a fast gluon in addition to a quark-antiquark pair. Two of these partons may have large transverse momentum. Our calculations lead to an intuitive picture of deep-inelastic diffractive processes which is very similar to Bjorken's aligned-jet model. Both diffractive structure functions contain leading twist contributions from high-$p_{\perp}$ jets.