Probing GPDs in Exclusive Electroproduction of Dijets Data

Abstract

We summarize the formalism for calculating the exclusive dijet production in 𝑒⁢𝑝 →𝑒′⁢𝑗⁢𝑗⁢𝑝 in collinear QCD factorization, using generalized parton distributions as the soft hadronic input modeled in the double distribution approach. We include all leading-order contributions coming from light sea and valence quark exchanges, and gluon exchanges for both light quark-antiquark production and also the heavy 𝑐 ⁢\bar𝑐 final state. We present results for several differential distributions for the cross section evaluated over a broad region of phase space, covering a wide range of inelasticity and photon virtuality. The gluon and sea contributions exhibit similar shapes, whereas the valence contribution, though relatively small, shows a markedly different behavior. The latter becomes particularly noticeable at large 𝑥ℙ, a kinematic region not explored at HERA, but potentially accessible in future measurements at the Electron Ion Collider. This requires further feasibility studies. We also present the azimuthal angle modulation between the leptonic and the outgoing dijet planes for the general case, as well as for the ZEUS kinematic region where we see reasonable agreement with the data for diffractive deep inelastic scattering parameter 𝛽 ≳0.4.