Inclusive prompt photon-jet correlations as a probe of gluon saturation in electron-nucleus scattering at small $x$

Understand

We compute the differential cross-section for inclusive prompt photon$+$quark production in deeply inelastic scattering of electrons off nuclei at small $x$ ($e+A$ DIS) in the framework of the Color Glass Condensate effective field theory.

• The result is expressed as a convolution of the leading order (in the strong coupling $\alpha_{\mathrm{s}}$) impact factor for the process and universal dipole matrix elements, in the limit of hard photon transverse momentum relative to the nuclear saturation scale $Q_{s,A}(x)$.
• We perform a numerical study of this process for the kinematics of the Electron-Ion Collider (EIC), exploring in particular the azimuthal angle correlations between the final state photon and quark.
• We observe a systematic suppression and broadening pattern of the back-to-back peak in the relative azimuthal angle distribution, as the saturation scale is increased by replacing proton targets with gold nuclei.