High Energy / Nuclear Theory / RIKEN Seminars

[NT/RBRC hybrid seminar] Probing gluon saturation via diffractive jet production at the EIC

by Dr Edmond Iancu (Institut de Physique Theorique de Saclay)




The study of the dense gluonic matter emerging in QCD at high energies represents one of the main goals of the experimental program at the future Electron-Ion Collider. We demonstrate that dijet production via inelastic diffraction is a promising channel for probing gluon saturation, including in the hard regime at high photon virtuality, where the collinear factorisation applies. By ``inelastic diffraction'' we mean a process in which the two hard jets -- a quark-antiquark pair generated by the decay of the virtual photon -- are accompanied by a softer gluon jet, emitted by the quark or the antiquark. This process can be described as the elastic scattering between an effective gluon-gluon  dipole and the nucleus.  The cross section takes a factorised form, between a hard factor and a unintegrated (``Pomeron'') gluon distribution describing the transverse momentum imbalance between the hard dijets. The dominant contribution comes from the black disk limit and leads to a dijet imbalance of the order of the target saturation momentum $Q_s$ evaluated at the rapidity gap.  Integrating out the dijet imbalance, we obtain a collinear factorisation where the initial condition for the DGLAP evolution is set by gluon saturation.