# Exclusive vector meson production at an electron-ion collider

## TL;DR

This paper calculates the distributions and cross-sections for exclusive vector meson production at an electron-ion collider, highlighting its potential to probe gluon structure, shadowing, and saturation effects in nuclei.

## Contribution

It provides detailed predictions for vector meson production across various states and energies, emphasizing detector requirements for future experiments.

## Key findings

- Large cross-sections for light and charm mesons.
- Upsilon states detectable at medium and high energies.
- Detector acceptance crucial for probing low Bjorken-x gluons.

## Abstract

Coherent exclusive vector meson electroproduction is a key physics channel at an electron-ion collider. It probes the gluon structure of nuclei over a wide range of $Q^2$, and can be used to measure nuclear shadowing and to search for gluon saturation and/or the colored glass condensate. In this paper, we present calculations of the kinematic distributions for a variety of exclusive vector meson final states: the $\rho$, $\phi$, J/$\psi$, $\psi'$ and the $\Upsilon$ states. The cross-sections for light and $c\overline c$ mesons are large, while $\Upsilon$ states should be produced in moderate numbers at a medium energy EIC (the proposed U.S. designs) and in large numbers at the LHeC. We investigate the acceptances for these states, as a function of detector rapidity coverage. A large-acceptance detector is needed to cover the full range photon-nucleon collision energies produced at an EIC; a forward detector is required to observe vector mesons from the most energetic photon interactions, and thereby probe gluons at the lowest possible Bjorken-$x$ values.