Coherent J/ψ Electroproduction on ^{4}He and ^{3}He at the Electron-Ion Collider: Probing Nuclear Shadowing One Nucleon at a Time.

While the phenomenon of gluon nuclear shadowing at small x has been getting confirmation in QCD analyses of various LHC measurements involving heavy nuclei, it has not been possible so far to establish experimentally the number of target nucleons responsible for nuclear shadowing in a given process. To address this issue, we study coherent J/ψ electroproduction on ^{4}He and ^{3}He in the kinematics of a future electron-ion collider and show that this process has the power to disentangle the contributions of the interaction with a specific number of nucleons k, in particular, with two nucleons at the momentum transfer t≠0. We predict a dramatic shift of the t dependence of the differential cross section toward smaller values of |t| due to a nontrivial correlation between x and k.

Selected topics in diffraction with protons and nuclei: past, present, and future.

We review a broad range of phenomena in diffraction in the context of hadron-hadron, hadron-nucleus collisions and deep inelastic lepton-proton/nucleus scattering focusing on the interplay between the perturbative QCD and non-perturbative models. We discuss inclusive diffraction in DIS, phenomenology of dipole models, resummation and parton saturation at low, hard diffractive production of vector mesons, inelastic diffraction in hadron-hadron scattering, formalism of color fluctuations, inclusive coherent and incoherent diffraction as well as soft and hard diffraction phenomena in hadron-hadron/nucleus and photon-nucleus collisions. For each topic we review key results from the past and present experiments including HERA and the LHC.

Nuclear shadowing and extraction of Fp2-Fn2 at small x from deuteron collider data.

We demonstrate that leading twist nuclear shadowing leads to large corrections for the extraction of the neutron structure function Fn2 from the future deuteron collider data both in the inclusive and in the tagged structure function modes. We suggest several strategies to address the extraction of Fn2 and to measure at the same time the effect of nuclear shadowing via the measurement of the distortion of the proton spectator spectrum in the semi-inclusive eD-->e'pX process.

Revealing the black-body regime of small-x deep-inelastic scattering through final-state signals.

We derive the major characteristics of inclusive and diffractive final states in deep-inelastic scattering off heavy nuclei for the high-energy (small-x) kinematics in which the limit of complete absorption is reached for the dominant hadronic fluctuations in the virtual photon (the black-body limit of the process). Both the longitudinal and transverse distributions of the leading hadrons are found to be strikingly different from the corresponding ones within the leading-twist approximation, and hence provide unambiguous signals for the onset of the black-body limit.