Accessing the gluonic structure of light nuclei at the Electron Ion Collider

TL;DR

This paper proposes using exclusive vector meson production at the Electron Ion Collider to explore the gluonic structure of light nuclei, revealing effects of nucleon interactions, substructure fluctuations, and evolution with energy.

Contribution

It introduces a detailed theoretical framework for probing small-x gluons in light nuclei using vector meson production, including effects of nucleon interactions and substructure fluctuations.

Findings

Short-range nucleon interactions influence $J/ ext{Psi}$ spectra.

Subnucleonic fluctuations significantly affect incoherent cross sections.

Predictions show $x$-dependence of cross sections and fluctuation scales.

Abstract

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 $^3$He wave functions. In particular, we demonstrate how short range repulsive nucleon-nucleon interactions affect the predicted coherent $J/\Psi$ production spectra. Fluctuations of the nucleon substructure are shown to have a significant effect on the incoherent cross section above $|t|\gtrsim 0.2\,\mathrm{GeV}^2$. By explicitly performing the JIMWLK evolution, we predict the $x$-dependence of coherent and incoherent cross sections in the EIC energy range. Besides 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 $|t|<1\,\mathrm{GeV}^2$, if subnucleonic spatial fluctuations are present.