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.

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.