Exclusive processes in $ep$ collisions at the EIC and LHeC: A closer look on the predictions of saturation models

TL;DR

This paper compares saturation models for exclusive vector meson and photon production in ep collisions, using recent HERA data to update models and predicting how future EIC and LHeC experiments can distinguish between different QCD dynamics approaches.

Contribution

It updates the Marquet-Peschanski-Soyez saturation model with new HERA data and compares its predictions with impact parameter models for future experimental discrimination.

Findings

Updated the MPS saturation model using recent HERA data.

Predicted distinct t-distributions for future EIC and LHeC experiments.

Showed that future measurements can differentiate between QCD models.

Abstract

The exclusive production of vector mesons and photons in $ep$ collisions is investigated considering three phenomenological saturation models based on distinct assumptions for the treatment of the dipole - hadron scattering amplitude. The latest high precision HERA data for the reduced and vector meson cross sections are used to update the saturation model proposed by Marquet - Peschanski - Soyez (MPS), which predicts that the saturation model is dependent of the squared momentum transfer $t$. The MPS predictions for the photon virtuality, energy and $t$ - dependencies of the exclusive $\rho$, $J/\Psi$ and DVCS cross sections are presented and a detailed comparison with the results derived using the impact parameter saturation models is performed. Our results indicate that a future experimental analysis of the $t$ - distribution $d\sigma/dt$ for exclusive processes in the kinematical range that will covered by the EIC and LHeC, considering the distinct photon polarizations and large values of $t$, will be able to discriminate between the distinct approaches for the QCD dynamics at high energies.