Accessing the gluonic structure of light nuclei at a future electron-ion collider

We show how exclusive vector meson production off light ions can be used to probe the spatial distribution of small-x gluons in the deuteron and 3He wave functions. In particular, we demonstrate how short-range repulsive nucleon-nucleon interactions affect the predicted coherent J/Ψ production spectra. Fluctuations of the nucleon substructure are shown to have a significant effect on the incoherent cross section above |t|≳0.2GeV2. By explicitly performing the Jalilian-Marian–Iancu–McLerran–Weigert–Leonidov–Kovner (JIMWLK) evolution, we predict the x dependence of coherent and incoherent cross sections in the electron-ion collider energy range. In addition to the increase of the average size of the nucleus with decreasing x, both the growth of the nucleons and subnucleonic hot spots are visible in the cross sections. The decreasing length scale of color charge fluctuations with decreasing x is also present, but may not be observable for |t|<1GeV2, if subnucleonic spatial fluctuations are present.